Preheat the oven to 350F.
Line the outside of the springform pan with tin foil and grease the cake pan liberally.
Line the bottom with the sliced apples in overlapping concentric circles.
To make the caramel sauce n a small saucepan melt the butter and sugar together, add in the salt, cinnamon, and stir well.
Pour the sauce over the apples and set aside.
Prep cake mix according to the instructions on the box and pour over the caramel & apples and bake as per instructions on the box.
Once done allow the cake to cool for about 15 - 20 minutes before removing it from the pan. To remove the cake from the pan, place a plate or cake stand upside down on the pan and invert the cake onto it. Then unlock the spring and slowly release the cake from the pan.
Serve warm. I always like to serve this with a side of caramel sauce and a dollop of vanilla ice cream.