- If making my homemade caramel sauce, make it first so it's set aside to cool while you work on the rest of the recipe. - 1/2 cup homemade caramel sauce 
- Preheat oven to 350 degrees F. 
- Make the apple pie filling: Peel, core, and chop the apples. Melt butter and cinnamon in a saucepan over medium heat, then stir in apples, sugar, and water. Cover and cook for 5-6 minutes, uncovering to stir every minute. In a small separate bowl, whisk together cornstarch with water. Add to the apples while stirring continuously. Remove from heat once the filling is thickened and bubbling. - 4 green apples, 2 tbsp butter, 1 tsp cinnamon, 5 tbsp granulated sugar, 1/4 cup water, 1 tbsp cornstarch 
- Transfer the apple pie filling mixture to a 9x13 pan, and spread evenly. 
- Drizzle 1/2 cup of the caramel sauce over the filling mixture evenly. 
- Sprinkle the cake mix over the filling. Do not mix. - 12 oz yellow or vanilla cake mix 
- Pour melted butter over the cake mix evenly, trying to cover as much of the cake mix as you can. - 3/4 cup butter 
- Bake for 45 minutes until golden brown on top and bubbly on the sides. 
- Cool slightly and serve warm with whipped cream, vanilla ice cream, and/or more caramel sauce.