Preheat oven to 350 degrees F. Place Reeses in freezer.

Beat together the butter, peanut butter and both sugars on medium speed until light and fluffy, about 3 minutes, scraping the sides of the bowl as needed. Add the egg and vanilla and mix, Reduce the mixer speed to low, add the dry ingredients, and mix until just combined.

Give the dough a final mix with a rubber spatula to ensure all of the flour is incorporated.

Plop dough into muffin tin.

Bake for 9 minutes, or until light golden brown and slightly puffy. While baking, unwrap reeses

Remove from the oven and immediately press a miniature peanut butter cup in the middle of each cookie, pressing down so that the top of the peanut butter cup is even with the top of the cookie. Cool for at least 10 minutes before removing from the pan.