Cream together softened butter, peanut butter, and brown sugar in the stand mixer bowl with the paddle attachment until combined and creamy, about 1 - 2 minutes.
Add egg, vanilla extract and continue to beat until light and fluffy, another 1 - 2 minutes.
In another mixing bowl, stir together flour, salt, baking soda, and baking powder. With the mixer on low speed, slowly pour flour mixture into the stand mixer bowl. Stir until incorporated.
Use a medium cookie scoop to scoop the cookie dough from the bowl, take a spatula and level off any excess cookie dough. Roll the dough into a ball with your hands. Place dough ball on a parchment-lined small baking sheet. This should yield 24 to 25 dough balls. Refrigerate for 30 minutes to an hour.
Preheat the oven to 375°F.
Take some cookie dough out of the fridge and place them on another parchment-lined baking sheets about 2 inches apart. Bake for 10 - 11 minutes. Bake one tray at a time in the middle of the oven. Keep the remaining cookie dough in the refrigerator.
Remove the baking sheet from the oven and place it on a wire rack to cool while you unwrap the chocolate. Gently press a chocolate heart in the middle of each cookie while it is still warm. Allow cookies to cool completely and the bottom of the chocolates to harden and stick to the cookies before moving them from the baking sheet.