Preheat oven to 375°F. Line baking sheets with parchment paper.

In a large mixing bowl, cream butter, peanut butter, granulated sugar, and brown sugar until light and fluffy.

Beat in the egg, milk, and vanilla extract.

In a separate bowl, whisk flour, baking soda, baking powder, and salt.

Add dry ingredients to the wet mixture and mix until just combined.

Shape dough into 1-inch balls, then roll each ball in granulated sugar.

Place on baking sheet about 2 inches apart.

Bake 8–10 minutes, or until the tops crack and edges look set.

Immediately press a chocolate kiss into the center of each cookie.

Allow cookies to cool on the baking sheet for 5 minutes before transferring to a cooling rack.