Once mixed, add 2 tablespoons of crunchy or smooth peanut butter depending whether you like nuts duh lol
Add the 15 (more or less) softened mini reeses's cups. Mix in til you really can't see big chunks anymore. Then bake the cake as directed.
For Frosting: Mix confectioner's sugar, 3 tablespoons of peanut butter (preferably smooth since it is for icing :), 2 tablespoons of softened butter. Add the milk VERY slow since it can make the icing way too liquidy.
Might wana add som reese's peanut butter cup chunks on the sides and/OR the top of the cake. I prefer the sides.