Place ½ cup granulated sugar in a medium bowl and set aside.
In a kitchen stand mixer, beat butter and peanut butter on low speed for at least 1 full minute, until smooth and combined.
Add ½ cup of granulated sugar, brown sugar, baking powder, and baking soda. Mix on low until all ingredients are fully combined.
Slowly add in the egg, milk, and vanilla, until combined, scraping the sides of the bowl occasionally.
Gradually add in the flour and beat until combined.
Shape the dough into little balls (about 1-inch each). Roll each ball into the bowl of sugar that you've set aside, until the entire dough is covered. Place the balls about 2 inches apart from each other on an ungreased
Bake at 350°F degrees for about 9-12 minutes. Remove once the bottoms are just slightly browned.
As soon as they are out of the oven, immediately press a milk chocolate candy kiss or 2-3 chocolate chips in the center of each cookie. Then using a wide spatula, gently lift each cookie and transfer to a wire rack to cool.