Preheat the oven to 350 degrees F (175 degrees C).
Spread apples in an even layer in a deep dish pie plate or 8-inch square glass casserole dish. Cover with white sugar, then top with cinnamon.
Combine flour and brown sugar for topping in a bowl. Add butter and cut in with a pastry blender. Spread topping evenly over apple mixture and pat down.
Bake in the preheated oven until apple mixture is bubbling and topping is browned, about 55 minutes.