1Heat oven to 350°F. Line 2 cookie sheets with cooking parchment paper or silicone baking mat.
2In large bowl, beat cake mix, butter and eggs with electric mixer on medium speed until well combined (batter will be very thick). Using 1-inch cookie scoop, drop dough about 2 inches apart onto cookie sheets.
3Bake 10 to 12 minutes or until set. Remove from cookie sheets to cooling racks; cool completely, about 15 minutes.
4Spoon frosting into small bowl. Add few drops red food color to make pink; stir until well blended. For each whoopie pie, spread desired amount of frosting on bottom of 1 cookie. Top with second cookie, bottom side down; gently press together.