Mix and bake off chocolate cupcakes according to the box mix instructions. Let them cool then stick them in the freezer.
(You can do this step a day ahead if you want. Freezing them helps when it comes to step 7.)
For the Peanut Butter Frosting: In a mixer with the paddle attachment cream butter and cream cheese until smooth. Add peanut butter and mix until combined.
Slowly add powder sugar to the peanut butter mixture on low. You want this to come together to where it feels more like a dough when you roll it between your fingers. Add powder sugar until you achieve this texture.
With clean hands take a golf ball size glob of the frosting out of the bowl and roll it in your hands into a ball then slightly flatten it to the size of the cupcake top. Set it on top of the cupcake then take your palms and flatten the sides of the icing to the top sides of the cupcake all the way around leaving a small dome in the center.
Once done to all the cupcakes stick them in the freezer to allow the icing to slightly freeze.
While the frosting is freezing take your chocolate and in a double broiler or in the microwave melt it. You may need to add a little vegetable oil to thin it out so its not so thick to dip. (I add around 1 tbsp of oil.)
**Add oil not water, water will cease the chocolate and make it lumpy!**
Once chocolate is melted take cupcakes out of freezer and one at a time turn over and dip the frosted top into the chocolate. This is where having the cupcake frozen comes in handy because if it isn't the top of the cupcake since it is now top heavy can fall off. (trust me its happened to me not fun)
Turn over the cupcake and set down, before the chocolate sets all the way decorate with sprinkles and Reese's cups.
Let the chocolate set up on the cupcakes (you can speed this up by sticking them in the refrigerator). ENJOY!!
**You should store these in the refrigerator since there is cream cheese in the frosting. **