Active Time

　　30 min

　　Total Time

　　2 hr

　　

Ingredients

Makes 12 squares

　　3 slices firm white sandwich bread, torn into quarters

　　

For shortbread base

1 1/2 sticks (3/4 cup) cold unsalted butter

　　2 cups all-purpose flour

　　1/2 cup packed light brown sugar

　　1/2 teaspoon salt

　　

For apple filling

1 1/4 sticks (1/2 cup plus 2 tablespoons) unsalted butter

　　2 lb tart apples

　　2/3 cup granulated sugar

　　2 tablespoons all-purpose flour

　　

Step 1

Preheat oven to 350°F.

　　

Prepare bread crumbs:

Step 2

Grind bread to fine crumbs in a food processor. Spread in a shallow baking pan and toast in middle of oven, stirring once, until golden, about 5 minutes. Leave oven on.

　　

Make shortbread base:

Step 3

Cut butter into 1/2-inch pieces, then pulse in a food processor with flour, brown sugar, and salt until it begins to form small lumps. Sprinkle base into a 13- by 9-inch baking pan and press evenly onto bottom. Bake in middle of oven until golden, about 20 minutes.

　　

Prepare filling while shortbread is baking:

Step 4

Melt butter and keep warm. Peel, quarter, and core apples and thinly slice quarters crosswise. Stir together sugar and flour in a small bowl.

　　

Assemble and bake squares:

Step 5

Sprinkle half of sugar mixture over hot shortbread, then top with apples and sprinkle with remaining sugar mixture. Top with bread crumbs and drizzle all of butter over them.

　　

Step 6

Bake in upper third of oven, pressing down on filling with a metal spatula halfway through baking, until apples are very tender and bread crumbs are golden, 50 minutes to 1 hour total. Cool 20 minutes in pan on a rack.

　　Cooks' note:

　　•Squares keep, covered and chilled, 3 days. Bring to room temperature before serving