Preheat the oven to 350* Degrees F. Line muffin tin with baking cups.
Prepare the cake batter according to the directions on the package, or according to your own from-scratch recipe.
Spoon batter into prepared baking cups.
Carefully add one teaspoon of room temperature hot fudge topping on the top of each cupcake.
Bake for about 16 minutes, or until toothpick comes out clean (test from the edge as the hot fudge will never come out clean on a toothpick).
Place on wire racks to cool.
Make your frosting by creaming butter and powdered sugar together on low speed. Once incorporated, increase mixer speed and add vanilla extract and milk. Beat on medium for about 2 minutes. If frosting is too stiff, add a little milk. If not stiff enough, add more powdered sugar.
Frost cupcakes when cool. Decorate with drizzled hot fudge and sprinkles.
Serve and Enjoy!