Preheat the oven to 350 F. In a large bowl, whisk together cake mix, eggs, and vegetable oil until smooth. Use a cookie scoop to place the cookie dough onto a large ungreased baking sheet at least 2-inches apart.
Bake for 10-12 minutes. Remove half of the cookies and set aside. Place one marshmallow, followed by one heart shaped chocolate on each cookie on the baking sheet. Bake for another 2-3 minutes. Remove from the oven, and sandwich each cookie with the remaining cookies.