Preheat the oven to 350 F. In a large bowl, mix together cake mix, eggs, vegetable oil, and peanut butter until smooth. Fold in the Reese's pieces candy.
Use a cookie scoop to place the cookies onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.
Remove form the oven, and place one chocolate heart on each cookie.