This recipe is from the Betty Crocker Cookbook (link). I think it's best when you add a handful of raisins or walnuts, but this recipe really is fool-proof and classic. Enjoy!
4 medium tart cooking apples, sliced (4 cups)
3/4 c packed brown sugar
1/2 c flour
1/2 c oats
1/3 c butter, softened
3/4 t ground cinnamon
3/4 t ground nutmeg
Cream or Ice cream (optional)
1. Heat oven to 375 degrees F.
2. Spread apples in 8" greased pan.
3. In medium bowl, stir remaining ingredients except cream until well mixed; sprinkle over apples.
4. Bake approximately 30 minutes or until topping is golden brown and apples are tender when pierced with a fork. Serve warm with cream.