Preheat the oven to 350F
Add the sliced apples, maple syrup, lemon juice, cornstarch, cinnamon, nutmeg, and salt to a large bowl. Toss everything together until the apples are evenly coated.
In another small bowl mix the topping ingredients besides the butter. Cut in the butter until the topping is crumb-like.
Add the apple mixture to a greased 8X8 pan, and sprinkle the topping mixture on top.
Bake for 45-50 minutes or until the topping is golden brown and the apple mixture is bubbling. Check at around 30 minutes to see if it is browning too fast. If it is, cover it with tin foil.
Once done cooking, cool on a wire rack for 10 minutes and top with ice cream or whipped cream!