Beat butter and peanut butter together until light and fluffy.

Slowly add in 1 C confectioners sugar. Add whipping cream until it reaches the consistency you desire.

Slowly add in the rest of the confectioners sugar, and then add in more whipping cream until it reaches your desired consistency.

Use a piping tip to fill a chocolate cupcake by pushing the tip into the top of the cupcake and gently squeezing to fill.

Add some to the top of the cupcake and sprinkle with Peanut Butter Cup crumbles.