Fruit Filling:
6 baking apples, peeled, cored, and cut into wedges
1 tablespoon lemon juice
1/2 cup sugar
2 tablespoons flour
Topping:
1 1/4 cups flour
1/2 cup rolled oats
1/2 cup light brown sugar
1/2 teaspoon ground cinnamon
1/4 teaspoon salt
12 tablespoons butter (1 1/2 sticks), chilled and cut into small pieces
1/2 cup nuts, coarsely chopped and toasted