Preheat oven to 350°. Line two baking sheets with parchment paper. Place an 8-inch round cake pan on top of paper and trace a circle onto paper. Turn paper over so that pencil mark is on the bottom. Repeat with second piece paper; set aside.
Combine cake mix and cocoa powder in large bowl. Add eggs, oil, water and food coloring and beat with electric mixer until blended. Divide batter in half and spoon onto center of traced circles on parchment. Spread batter with spoon to the edge of each circle.
Bake, rotating baking sheets once, 15 minutes, or until toothpick inserted in centers comes out clean. Cool completely on wire racks.
Combine cream cheese and confectioners sugar in medium bowl and beat with electric mixer until smooth and creamy. Reserve 3 tablespoons.
Remove paper from cake. Place 1 cake layer flat side up on serving platter. Spoon Breyers® Homemade Vanilla Ice Cream onto cake and spread into an even layer to edge of cake. Place remaining cake layer flat side up on flat surface. Evenly spread cream cheese mixture on cake to edge. Place cake, cream cheese side down, on top of ice cream layer to make whoopie pie. Freeze 1 hour.
Combine reserved 3 tablespoons cream cheese mixture with milk in small bowl until smooth. Drizzle over top of whoopie pie. Serve immediately.
See nutrition information for fat, saturated fat and cholesterol content.