Summer casserole

A PLATEFUL: Rustic vegetable casserole. (Bob Chamberlin / Los Angeles Times)

Total time: 1 3/4 hours (includes 45 minutes baking time)

Servings: 12 to 16

Note: This recipe can be halved to feed a smaller crowd.

7 tablespoons olive oil, divided

3 tablespoons sherry vinegar

4 cloves garlic, chopped

1 large red onion, cut in half lengthwise then sliced into 1/4 -inch slices

Kosher salt

Freshly ground black pepper

12 large basil leaves, torn into pieces (1 cup, loosely packed)

4 large tomatoes, cored, seeded and chopped into 1 1/2 -inch pieces

3 ears corn, husked, kernels cut off (about 4 cups)

3 1/2 pounds summer squash (zucchini, yellow squash, patty pan squash, etc.), seeded and chopped into 1 1/2 -inch pieces

3 cups coarse, fresh breadcrumbs, preferably whole wheat

1/4 cup fresh lemon juice, divided

3 tablespoons melted butter

2 tablespoons chopped mixed herbs (such as thyme, rosemary and flat-leaf parsley)

1 cup shredded Gruyère cheese

1/2 cup sour cream or plain Greek-style yogurt

1. Heat the oven to 350 degrees. Grease a 9-by-13-inch baking dish with 1 tablespoon of the oil; set aside.

2. Heat 3 tablespoons of the remaining oil in a large, deep skillet over medium-high heat. Add the vinegar, garlic, onions, one-half teaspoon salt and one-eighth teaspoon pepper and cook, stirring occasionally, until softened and golden, about 10 minutes.

3. Add the basil, tomatoes and corn and cook until the tomatoes have released their liquid, 6 to 8 minutes. With a slotted spoon, transfer the tomato-corn mixture to prepared baking dish.

4. Return the skillet to the stove and add the remaining 3 tablespoons of oil, the squash, one-half teaspoon salt and one-eighth teaspoon pepper and cook, stirring occasionally, until softened and just golden-brown in parts, 12 to 14 minutes. Meanwhile, in a medium bowl, toss the breadcrumbs with 2 tablespoons of the lemon juice, butter, herbs, one-fourth teaspoon salt and a pinch of pepper, just until combined.

5. Transfer the squash to the dish with the tomato-corn mix. Add the Gruyère, sour cream (in dollops), and the remaining 2 tablespoons lemon juice and half of the breadcrumbs and toss together gently to combine. Top with the remaining breadcrumbs; bake until golden brown and bubbling, about 45 minutes. Serve immediately.

Each serving: 184 calories; 6 grams protein; 15 grams carbohydrates; 3 grams fiber; 13 grams fat; 5 grams saturated fat; 16 mg. cholesterol; 206 mg. sodium.