1. Line a baking sheet with parchment paper and set it aside.

2. Combine the cake mix, eggs, vegetable oil, and vanilla in a large bowl. Add the green food coloring and mix well to incorporate it evenly.

3. Chill the dough in the refrigerator for 20 minutes.

4. Preheat the oven to 350°F. Mix the confectioners sugar and cornstarch in a small bowl.

5. Remove the dough from the refrigerator. Scoop dough into 1 inch balls, roll in the confectioners sugar mixture until completely coated, and place on baking sheet 2 inches apart.

6. Lightly press down with the bottom of a glass to make the balls have a flatter surface. (Do not press too hard though).

7. Add the candy heart to the top of the dough ball, gently pressing it down into the dough a little bit.

8. Place the baking sheet in the oven and bake for 8-10 minutes. Do not overbake.

9. Cool on cookie sheet for 3-4 minutes before transferring to a cooling rack to cool completely.