Slowly it turns, step by step . . .

A grilled cheese sandwich is an ode to childhood, a purist’s dream and an archetypal comfort food all at once. Just three mundane ingredients and a few minutes should be all it takes to create something downright sublime, right? So why do so few sublime ones come our way?

As with other minimalist dishes -- an omelet, say, or a plate of pasta -- there are a lot of assumptions that can get in the way of the cooking, assumptions that need to be jettisoned before the dish can reach its true potential.

When done right, an exemplary grilled cheese sandwich is not grilled at all (it’s toasted). Nor is it quick. And it certainly doesn’t shine when it’s assembled from just any cheese or bread. But combine slow griddling over a low flame with a cave-aged Gruyère, a loaf of freshly baked country bread and a nub of Normandy butter, and you’ll have a simply made dish that approaches greatness.

High-quality bread, butter and cheese are already a magical combination; when toasted, that magic becomes transformative. The ingredients undergo a rough alchemy, the butter browning, the bread crisping, the cheese melting into a glorious synthesis, shot through with a rich, caramelly perfume.

This magic is so strong that for many of us, it worked throughout childhood with squares of American cheese, pillowy white bread and margarine. Imagine the results with artisan cheeses, terrific bakery bread, creamy butter -- maybe some stone-ground mustard or slices of heirloom tomatoes -- and, importantly, a little grown-up patience.

Because along with great ingredients, the secret to a perfect grilled cheese sandwich is in the timing. Don’t rush it. The bread needs slow encouragement to crisp evenly; the cheese is best when it’s coaxed into melting.

In spite of its name, a grilled cheese sandwich should not be grilled. The bread will char long before the cheese melts. A cast-iron pan or griddle works best because it retains and diffuses the heat more effectively than other pans. You’ll also need a weight or press.

Slow diffusion of heat and weighting the sandwich allow for even cooking and happy results -- a wide expanse of golden bread and, above that, an even field of melted cheese. Cooking it evenly means that when you flip the sandwich, the process continues on the other side: no pockets of unmelted cheese, no periphery of untoasted bread, no soggy interior.

To compress the sandwich, many restaurants use a panini press, which is like a flatter version of a waffle iron. At Campanile in Los Angeles, where Grilled Cheese Night has become an institution, large sandwich presses are set up behind the bar every Thursday. (If you have one, a George Foreman grill would work similarly, says chef Mark Peel.)

But at home, the easiest thing is to place a second, smaller cast-iron pan on top of the sandwich as it cooks or, even better, take a cue from MeltDOWN in Culver City, a new eatery entirely devoted to the owners’ obsession with grilled cheese sandwiches, and use a steak weight.

Shaped like a trowel and about the size of a brick, it’s sometimes called a bacon press and is available in cookware stores. Though it’s designed for cooking steaks, it works perfectly on sandwiches. As Judy Rodgers recommends in “The Zuni Cafe Cookbook,” you can also press the sandwich down as it rests on a cutting board before it even goes into the pan.

The weight condenses the cheese, pressing out air pockets, and flattens the edges of the bread so they remain pressed firmly against the heated surface.

The best bread for making grilled cheese sandwiches is freshly made and sliced (ask the bakery to do it when you choose the loaf so that you have uniform half-inch slices) -- maybe a country white sourdough or a light whole wheat. Dense whole-grain loaves tend to be too heavy; baguettes and some ciabattas can be shot through with air pockets -- gorgeous when sliced, maybe, but not the best vehicle for melting cheese. And though you might think that stale bread would make pretty good grilled cheese sandwiches, the already brittle crumbs can become like shards when crisped.

Choose a cheese that melts well, neither as hard and pungent as Parmesan, nor as soft and creamy as a Camembert or a fresh goat cheese. Even when grated, harder cheeses won’t melt satisfactorily, and soft cheeses won’t hold up to the cooking but will leak out of a sandwich and into the pan.

Widely available cheeses such as Gruyère, Fontina and Emmentaler are fantastic for this purpose, as are the whole gamut of cheddars, made in Wisconsin or Vermont or England, aged for six months or three years, or maybe smoked over apple wood. Blue cheeses, if not too gooey or overwhelmingly pungent, can make for pretty tasty sandwiches too. Be sure to slice the cheese very thinly, or better yet, grate it. It’s a bit messier, but it melts the most evenly.

You can also play with flavor profiles (and textures) and mix two or even three cheeses. Just be careful to match cheeses that have complementary flavors and melting points, and be careful not to overdo it.

With a terrific cheese, it’s easy to think that more is better, but restraint is actually crucial to a good sandwich. There should be a good proportion of bread to cheese, about twice as much bread as cheese. Though this ratio can vary according to taste, too much cheese can be overwhelming. (If this becomes a recurrent problem, consider making fondue instead.)

To bring it all together, choose a good butter; if you’re feeling particularly decadent, try salted Normandy butter. It adds a certain extra luxuriousness to the sandwich, and the added hint of salt further brings out the flavors of the bread.

Some chefs swear by clarified butter (butter that has been rendered to remove the milk solids and water from the butter fat), as it has a much higher smoking point. But because you’re cooking the sandwiches over low heat, this really isn’t an issue. Either way, melt the butter first, as it makes it easier to move the sandwich from the cutting board to the pan, and to weight it without the butter sticking to the various surfaces.

You could also brush the bread with a fruity olive oil for a more robust, earthy flavor, which is a nice option with an aged goat cheese or a nutty Emmentaler. And, if you use a mild cheese such as Fontina or Muenster, try infusing the olive oil with fresh sage leaves, peppercorns or rosemary. Or use a combination of olive oil and butter.

Though a purist will stop here, you can also embellish a grilled cheese sandwich with further accouterments. Torque up the classic Gruyère and country white sandwich with a smear of whole-grain mustard and some marinated onions like Peel does at Campanile. Add smoked ham or apple-wood-smoked bacon to a robust blend of sharp cheddar, Muenster and Fontina, the most popular sandwich on the menu at MeltDOWN.

Experiment with flavor combinations: Spread rosemary bread with tangy apple butter for a spin on the traditional pairing of apples and cheddar. Match fig preserves with an aged goat cheese and walnut bread, or put together a smear of chestnut honey with a rich Basque blue cheese and crisp raisin brioche. You can spread the preserves or honey on the bread before adding cheese and griddling it -- or add a spoonful to the plate for casual dipping.

Sandwich in a few thin discs of pear with a mild blue cheese, thin slices of prosciutto with Fontina or the heirloom tomatoes now gracing the market stalls with Gruyère. But take a tip from “Nancy Silverton’s Sandwich Book” (born of Grilled Cheese Nights) and add the tomatoes after the sandwich is cooked.

Let a few slices of tomato sit under a brief pour of olive oil and a sprinkle of sea salt while you cook your sandwiches. When the sandwiches emerge from the pan, burnished and redolent of melted cheese, pry them open and gently slide in the tomatoes.

It’s the perfect solution, too, for other delicate add-ins that can’t stand up to the heat of the pan -- such as fresh herbs, tender baby lettuces, a slice of ripe peach or even a fried duck egg.

Like many true comfort food classics, a grilled cheese sandwich comes trailing clouds not of glory precisely, but of memory. And though you can’t revise your childhood, even your therapist would agree that you’re free to revamp your favorite grilled cheese sandwiches to your heart’s content.

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amy.scattergood@latimes.com

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Fontina and sage grilled cheese

Total time: About 20 minutes, plus pressing time for the sandwiches

Servings: Makes 2 sandwiches

Note: Adapted from “The Zuni Cafe Cookbook” by Judy Rodgers.

3 tablespoons best-quality olive oil, plus a few drops for the pan

1 dozen fresh sage leaves, chopped (about 1 tablespoon)

1/2 teaspoon freshly ground black pepper

4 ounces Fontina cheese, rind removed and coarsely grated

4 slices country white bread

1. In a small saucepan over low heat, heat the olive oil, sage and pepper until warm to the touch. Turn off the heat and let it infuse while you assemble the sandwiches.

2. Place the cheese, divided evenly, on two slices of bread. Take care to bring the cheese all the way to the edge of the crust. Top each with a second slice of bread and press flat. Lay a heavy or weighted cutting board on top of the sandwiches for 10 to 20 minutes.

3. Use a pastry brush to spread the sage oil lightly on both sides of the sandwiches. Make sure you go all the way to the edges, and try to distribute the sage and pepper evenly over the bread.

4. Heat a cast-iron pan or griddle over low heat. Sprinkle with a few drops of olive oil, then rub it over the whole cooking surface with a paper towel. Add the sandwiches and cook, weighted with another heavy pan or a steak weight, until golden, about 2 to 3 minutes per side. Keep the heat low so that you don’t burn the sage or pepper.

5. Remove the sandwich to a cutting board and cut it in half or in quarters. Serve immediately.

Each sandwich: 565 calories; 20 grams protein; 31 grams carbohydrates; 2 grams fiber; 40 grams fat; 14 grams saturated fat; 66 mg. cholesterol; 804 mg. sodium.

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Grilled Gruyère and marinated onion sandwich

Total time: About 25 minutes, plus marinating time for the onions

Servings: Makes 2 sandwiches

Note: Adapted from Campanile chef-owner Mark Peel

1/2 cup Spanish or brown onion, very thinly sliced

1/4 teaspoon kosher salt

1/4 teaspoon freshly ground black pepper

1 tablespoon best-quality olive oil

1 tablespoon white wine vinegar

4 slices country white bread

4 tablespoons salted butter, melted

5 ounces Gruyère cheese, coarsely grated

4 teaspoons stone-ground mustard

1. In a small bowl, mix together the onion, salt, pepper, olive oil and vinegar. Cover and let sit for at least 1 hour.

2. Heat a cast-iron pan or griddle over low heat. Brush one side of each slice of bread with the melted butter. Place two slices of bread, butter-side down, on a cutting board. Spread half of the grated cheese evenly over the bread. Drain the excess liquid from the marinated onions and scatter them evenly over the cheese-topped slices. Distribute the remaining cheese evenly over the onions. Spread the mustard over the unbuttered sides of the remaining 2 slices of buttered bread. Place these, mustard-side down, on top of the slices spread with cheese.

3. Using a spatula, place one of the sandwiches into the hot pan and weight with another heavy skillet or a steak weight. (If your pan is big enough, cook both sandwiches; otherwise, cook one at a time.) Cook until golden brown, about 3 to 4 minutes. Flip the sandwich and weight it with the pan or steak weight, and cook until golden brown, another 3 to 4 minutes.

4. Remove the sandwich to a cutting board and cut it in half or quarters. Serve immediately.

Each sandwich: 745 calories; 29 grams protein; 37 grams carbohydrates; 2 grams fiber; 55 grams fat; 29 grams saturated fat; 138 mg. cholesterol; 1,131 mg. sodium.

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Grilled blue cheese and pear sandwich

Total time: About 25 minutes

Servings: Makes 2 sandwiches

Note: Raisin brioche is available from La Brea Bakery; you can substitute any good-quality raisin bread. Bleu des Basques cheese is available from Nicole’s Gourmet Foods in South Pasadena, the Cheese Store of Silverlake and the Cheese Store of Beverly Hills.

4 slices raisin brioche

2 tablespoons salted butter, melted

4 ounces firm but mild blue cheese, such as bleu des Basques, crumbled

1 pear, slightly under-ripe, cored and thinly sliced

Chestnut honey for drizzling, optional

1. Heat a cast-iron pan or griddle over low heat. Brush one side of each bread slice with melted butter.

2. Spread half of the cheese evenly over the unbuttered side of two slices of the bread. Place a single layer of the pear slices over the cheese, then top with the remaining cheese. Place the remaining bread on top of each sandwich, buttered-side up.

3. With a spatula, place one of the sandwiches into the heated pan and weight it with a second heavy pan or a steak weight. (If your pan is large enough, cook both sandwiches; otherwise, cook them one at a time.) Cook until golden brown, about 3 to 4 minutes. Flip the sandwich, weight it with the pan or steak weight, and cook until golden brown, another 3 to 4 minutes.

4. Remove the sandwich to a cutting board and cut it in half or quarters. Serve immediately with a drizzle of chestnut honey, if desired, on the plate.

Each sandwich: 524 calories; 18 grams protein; 48 grams carbohydrates; 5 grams fiber; 31 grams fat; 18 grams saturated fat; 73 mg. cholesterol; 1,122 mg. sodium.

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Grilled cheddar cheese with apple butter

Total time: About 25 minutes

Servings: Makes 2 sandwiches

Note: Apple-wood-smoked cheddar is available at well-stocked supermarkets and fine cheese counters. You can substitute any best-quality cheddar.

4 slices rosemary bread

2 tablespoons salted butter, melted

6 ounces apple-wood-smoked cheddar cheese, coarsely grated

2 tablespoons unsweetened apple butter

1. Heat a cast-iron pan or griddle over low heat. Brush one side of each bread slice with the melted butter.

2. Spread half the cheese evenly over the unbuttered sides of two slices of bread, carefully spreading it to the edges. Spread 1 tablespoon of apple butter over each of the unbuttered sides of the two remaining slices, then place them, apple-butter side down, onto the slices spread with cheese.

3. With a spatula, place a sandwich into the heated pan and weight it with a second heavy pan or a steak weight. (If your pan is large enough, cook both sandwiches; otherwise, cook them one at a time.) Cook until golden brown, about 3 to 4 minutes. Flip the sandwich and weight it with the pan or steak weight, and cook until golden brown, another 3 to 4 minutes.

4. Remove the sandwich to a cutting board and cut it in half or quarters. Serve immediately, with extra apple butter if desired.

Each sandwich: 782 calories; 26 grams protein; 46 grams carbohydrates; 2 grams fiber; 54 grams fat; 27 grams saturated fat; 158 mg. cholesterol; 769 mg. sodium.