Preheat the oven to the box directions. Prepare the cake mix according to directions. Coring and slicing the apples, mixing them in with the cake mix. Bake until knife comes out clean.
While the cake is cooking, prepare the Caramel sauce.
In a saucepan, pour 1 cup of sugar on MEDIUM heat until it is completely melted. It will start to brown, make sure you continue to stir so it doesn't burn.
Put in the cut up chunks of butter, CAREFUL -- the butter makes the mixture very bubbly.
Once the butter is completely melted, slowly pour in the heavy cream, it will start to rise. Allow it to boil for 1 minute.
Remove from heat and stir in the salt. Set aside.
Once the cake comes out, poke holes in it, and pour the entire can of Sweetened milk over the cake. Pour the caramel over the cake, (leaving a little to drizzle over the top -- optional) using a rubber spatula, push the caramel and milk around the top of the cake, making sure its completely covered.
Once the cake is COMPLETELY cooled down, top it with the whipped topping, drizzling the remainder of the caramel on top.
Serve as is or with a scoop of vanilla ice cream!
