Active Work Time: 30 minutes * Total Preparation Time: 45 minutes plus 1 hour chilling
1 tablespoon granulated sugar
1/2 cup (1 stick) unsalted butter
1/2 cup brown sugar, packed
1/4 teaspoon salt
1 teaspoon vanilla extract
1 egg yolk
1 1/4 cups flour
Grind or pulse the hazelnuts with the granulated sugar in a food processor until fine, but with a few chunks scattered throughout. Cream the butter and brown sugar with the salt until light and fluffy, then stir in the vanilla and egg yolk. Stir in the hazelnuts and the flour.
Shape the dough into a rough log, wrap it in wax paper or plastic wrap, then run the dough between your thumb and forefinger to force it into a cylinder about 1 1/2 inches in diameter. Keep it round, or square the sides. Refrigerate the dough until firm, at least 1 hour, preferably longer.
Heat the oven to 350 degrees.
Cut the log into 1/3- to 1/4-inch thick slices and place them on 2 baking sheets, leaving at least 2 inches between each piece. Bake until lightly browned on top, about 15 minutes. Remove the crisps to a rack to cool; they'll get crispier.
About 27 crisps. Each crisp: 98 calories; 24 mg sodium; 17 mg cholesterol; 6 grams fat; 2 grams saturated fat; 10 grams carbohydrates; 1 gram protein; 0.57 gram fiber.