Preheat the oven to 350F, and prepare about 20 cupcake liners in muffin pans.

In medium bowl, whisk together flour, cocoa, baking powder, baking soda, and salt.

In a measuring cup, mix together Bailey's and vanilla.

In a stand mixer, at low speed, beat butter and sugar till blended. Increase speed to high and beat for 2 minutes. Reduce speed to medium-low and add eggs one at a time, beating well after each addition.

With mixer at low speed, alternatively add the flour mixture and the milk mixture, starting and finishing with the flour. Beat until batter is smooth, occasionally scraping bowl with a spatula. Divide batter evenly among your prepared cups. The cupcake cups I used are larger than standard so I got 14, but you should get more with smaller cups!

Bake cupcakes for 30-35 min, until top is puffy and a toothpick inserted in the center comes out clean. Let cool completely before frosting.

Now, prepare the frosting. In the bowl of a stand mixer fitted with the whisk attachment, beat together the butter and cream cheese until smooth and creamy.

Add in the Bailey's or vanilla, then add in the powdered sugar, one cup at a time. Finally add in a sprinkle of salt.

Divide the frosting into 7 small bowls, and color each as desired.

Place a large piece of saran wrap on the countertop, and spoon the frosting into a long and skinny line for each color. It should basically look like a straight rainbow (see image below). Carefully roll up the saran wrap and twist the ends tightly.

Prepare a large decorating bag with a piping tip {I used 1M}, then place the saran wrap roll inside. Pull one of the twisted ends through the open end of the decorating tip, and cut with scissors. Now you can decorate your cupcakes! Pipe frosting as desired and top with gold sprinkles. Enjoy!