First, prepare the crumble topping. In a medium bowl whisk together flour, oats, brown sugar, sugar, salt, and cinnamon. Cut in the butter with a pastry knife, or two forks, or with your hands until mixture is crumbly. Set aside.
Peel and chop 4 of the apples. Add chopped apples, butter, brown sugar, and cinnamon to a medium sauce pan and sauté over medium heat for 8-10 minutes or until apples are tender. Remove from heat.
Chop the tops off of the remaining 4 apples and use a spoon to scoop out the flesh. Discard the flesh.(See Note) You don't need to get every little bit out, just enough to make a "bowl" for the filling.
Fill scooped-out apples with apple filling from the sauce pan. Top with a generous amount of crumble topping.
Place stuffed apples on a baking sheet and bake for 10-15 minutes until crumble topping is crispy. Serve warm topped with slab of butter.
*If you have an apple corer, you can remove the core and use some of the flesh in the filling in which case you won't need 4 whole apples for the filling, probably 3.