Pre-heat oven to 350 degrees.
Because I usually only want about 25-30 of these cupcakes, I usually only make half a cake mix.
If using stand mixer, fit with paddle attachment.Pour cake mix into bowl. Add in water, oil and eggs .Beat on high speed for 1-2 minutes.
Line your mini muffin tin with mini muffin wrappers. This is a must because otherwise the peanut butter cups will stick to the bottom of the pan and be a gooey mess. Drop unwrapped mini peanut butter cups into the bottom of the cupcake wrappers.
Fill the cupcake wrappers with batter (only 3/4 of the way full).
Bake at 350 degrees for about 15 minutes (mini cupcakes don't take too long).
Allow to cool completely.
Frost with chocolate peanut butter buttercream. I like to pipe a swirl on top using a star tip but you can frost however you like.Enjoy!