Spray a mini muffin pan with non-stick cooking spray.
Preheat oven to 350*F.
Prepare sugar cookie dough according to bag directions (or prepare sugar cookie dough using your favorite recipe).
Roll dough into small balls (about 1 tablespoon), and fill mini muffin tin with one ball of dough in each space.
Bake cookies 8-10 minutes, or until the cookies are golden brown on the edges, but still a bit soft in the center.
While the cookies bake, unwrap the mini peanut butter cups.
Remove tray from oven, and press one peanut butter cup into each warm cookie.
Allow cookies to cool (in pan). The peanut butter cup will melt a bit, but then firm up as the cookies cool.
Once cool, remove from pan.
If desired, melt a bit of chocolate and drizzle over cool cookies, or add some festive sprinkles (while the peanut butter cup is still a little melty).