Preheat the oven to 350 degrees. Put parchment paper on two baking sheets.
In a large bowl, mix together the butter, peanut butter, brown sugar, and white sugar.
Mix in the egg, milk and vanilla, until well combined.
Add in the flour, baking powder, and salt. Mix until well combined, and a dough forms.
Put the cookies onto the baking tray, roughly two inches apart in the shape of balls, and bake for 10-12 minutes.
Remove from the oven, and immedietly place the hearsheys kisses in the center of the cookie.
Enjoy cooled or still warm.