PREHEAT oven to 375°F. Place apples in greased 9-inch square baking pan.
MIX flour, brown sugar, cinnamon and nutmeg in large bowl; cut in margarine with pastry blender or 2 knives until mixture resembles coarse crumbs. Stir in walnuts; spoon evenly over apples.
BAKE 20 to 30 minutes or until apples are tender and topping is lightly browned.