Not sure why I haven’t made this before, but we could literally eat ALL of this frosting, sans the cupcake part.
We celebrated a VERY dear friend’s birthday yesterday, and here is the safe dessert we made.
Chocolate on Chocolate Cupcakes

• 3 sticks unsalted butter
• 5 cups powdered sugar
• 1 cup safe powdered unsweetened cocoa (Vermont nut-free or Hershey’s)
• Splash milk (optional)
• Splash vanilla extract 

Directions

• Make a devils food Betty crocker cake mix as directed, we did cup cakes
• Bake and cool completely
• In electric mixer bowl, cream together the room temperature butter and one cup of sugar at a time until creamy smooth. 
• Add remaining ingredients. Mix slow at first, then medium.
• Stop mixing and check the beaters. If the frosting doest slide off the beaters, and it tastes delish, it’s good to go!