Preheat oven to 375°F (190°C).
Place apple slices evenly in a greased 8-inch square baking dish.
In a medium bowl, mix brown sugar, flour, oats, cinnamon, and nutmeg.
Cut in softened butter until mixture resembles coarse crumbs.
Sprinkle the mixture evenly over apples.
Bake for 30-35 minutes or until apples are tender and the topping is golden brown.
Serve warm with vanilla ice cream, if desired.