In the bowl of a stand mixer or using a hand mixer, cream the butter and peanut butter together.

Add both sugars and mix until blended.

In a separate bowl, mix together the egg, milk and vanilla and add to the stand mixer. 

Continue to mix until everything is combined and smooth.

Combine the dry ingredients in a separate bowl.

Once combined, add the flour mixture to the peanut mixture one cup at a time, beating between each addition.

Place the dough in the refrigerator to chill for at least 30 minutes.

While the dough is chilling, preheat oven to 375°F and prepare a baking sheet by lining with parchment paper.

After the dough has chilled, use a tablespoon size cookie scoop to scoop out dough and form each scoop into a ball.

Place the extra ⅓ cup granulated sugar in a small bowl and roll each dough ball in the sugar until coated. 

Place each coated dough ball on the prepared baking sheet two inches apart to allow for spreading.

Bake cookies 8 to 10 minutes, or until the cookies are golden brown and puffy.

Remove the cookies from the oven and press a chocolate heart-shaped candy into the center of each cookie.

Allow the cookies  to cool on the baking sheet for five minutes before removing to a wire cooling rack to cool completely.