For cupcakes: Whisk together all ingredients.

Fill cupcake liners 2/3 full and bake at 350º for 19 minutes.

For buttercream: In a stand mixer, cream together the butter and shortening.

Add the powdered sugar and the caramel alternately (add the salt in with the caramel), mixing after each addition.

Add milk, by the tbsp. as needed for thinning

*The caramel is a little tricky just in that it needs to be the right temperature-- warm enough that it's still liquid and can blend into the buttercream, but not so hot that it melts the butter making everything too thin. Evaluate the buttercream at about 4 tbsp of caramel-- if it's getting way too thin, stop adding caramel or add more powdered sugar. I found that 6 Tbsp. was perfect for my batch.