Preheat the oven to 375 degrees.
Prepare the mini-cupcake tins by spraying with cooking spray.
Cream butter and peanut butter until totally combined.
Add both sugars and cream together for 3 minutes.
Add egg and beat until well combined.
Add vanilla and blend.
Combine the flour, baking soda and salts.
Add the flour mixture to the butter mixture.
Mix just until the flour mixture is well incorporated, but do not over-mix.
Roll into 1-inch balls and place one in each mini-muffin cup.
Bake 8 1/2-10 minutes - just until they start turning a little darker brown.
Remove from the oven and press one peanut butter cup into the middle of each muffin.
Let cool and set for 2 minutes, then remove carefully (I use a thin table knife) and place on a cooling rack.
If the cookies fall apart when trying to remove from the pan, wait another minute and they should come out okay.)
These freeze well. The taste will stay the same, but the chocolate might have a little bit different look.