Heat oven to 350° F. Prepare two cookie sheets by lining with parchment paper (my preferred method), or use a silpat liner or cooking spray.
Unwrap the heart chocolates and place them inside a bowl. Allow the chocolate to refrigerate while you prepare the cookie dough.
In a small mixing bowl, stir together the flour, baking soda, baking powder, and salt with a wire whisk. Set aside.
In a larger mixing bowl with a hand mixer, or you can use a stand mixer, add the peanut butter, butter, sugar, and brown sugar. Beat on medium-low speed, for about 2 minutes, until combined well and lighter in color.
Add the egg and vanilla extract. Mix until combined.
Add the flour mixture and mix on low speed until incorporated and no flour streaks remain in the dough.
Place the additional ⅓ cup of granulated sugar into a small bowl.
Use a small cookie scoop, or about 1.5 tablespoons of dough, and scoop up the cookie dough. Roll into a ball and then roll the ball in the sugar until it's completely coated all around. Place 12 cookies per cookie sheet.
Bake for 9-12 minutes. Cookies will look puffy and have slight cracks on the tops.
Remove from the oven and immediately press a heart shaped chocolate (from the fridge) onto the top of each cookie. Let the cookies cool on the cookie sheet for about 15 minutes and then remove them to a cooling rack to cool completely.