- 1 1/2 cups all-purpose flour
- 1 1/8 cups old-fashioned oats
- 1 1/8 cups packed light brown sugar
- 1 1/2 cup walnuts (5 ounces), toasted , cooled, and finely chopped
- 1 1/2 teaspoons cinnamon
- 3/4 teaspoons salt
- 1 1/2 sticks (3/4 cup) unsalted butter, cut into 1/2-inch cubes and softened
- 4 1/2 pounds sweet-tart apples such as Gala
- 3 tablespoons fresh lemon juice
- 4 1/2 tablespoons granulated sugar, or to taste
- 2 tablespoons all-purpose flour
- whipped cream or vanilla ice cream
- Put oven rack in middle position and preheat oven to 375°F. Butter a 12- by 9- by 2-inch glass or ceramic baking dish (3 to 3 1/2 quarts.
- Stir together flour, oats, brown sugar, walnuts, cinnamon, and salt in a bowl, then blend in butter with your fingertips until mixture forms small clumps.
- Peel and core apples and cut into 1/4-inch-thick wedges, then toss with lemon juice, granulated sugar, and flour in a large bowl. Transfer to baking dish, spreading evenly.
- Crumble oat topping evenly over apple mixture and bake until topping is golden and apples are tender, about 45 minutes. Cool slightly and serve warm.