Cut a small piece out of the center of each cupcake.
Spoon caramel sauce into the hole. Frost with chocolate frosting. Top with a Sea Salt Butterscotch Caramel (from Trader Joe's), if desired.
For the Chocolate Frosting:
Melt butter. Stir in cocoa. Alternately add powdered sugar and milk, beating to spreading consistency. Add small amount additional milk, if needed. Stir in vanilla. Makes about 2 cups frosting.