In the bowl of a stand mixer, beat the cake mix, pudding, eggs, sour cream, oil, and milk on medium speed for 1-2 minutes. Use a rubber spatula to scrap down the sides of the bowl as needed.
Scoop the cupcake batter into the muffin cups, filling it no more than 2/3 of the way full.
Bake for 20 minutes or until a toothpick comes out with only a couple of crumbs. Remove from the oven and cool completely on a wire rack.
After they have cooled, carve out a small hole in the top of each cupcake.
Fill with a teaspoon of caramel sauce.
In a large bowl, beat the butter and vanilla together on medium-high speed.
Add half of the powdered sugar at a time. Beat on medium-low speed until thick and fluffy. Then add the salted caramel while the mixer is running and whip until it’s smooth.
Mix in the whipping cream. Transfer the frosting to the piping bag.
Pipe swirls of the salted caramel frosting on top of the cupcake. Repeat until all are decorated.
Drizzle with additional caramel sauce and serve.