Preheat oven to 350ºF and line two baking sheets with parchment paper.
Make Devil's food cake batter according to the directions on the box but add 1 extra egg. Pour half of the batter onto one baking sheet and spread it out until it covers the baking sheet. Repeat with the rest of the batter.
Bake for 20 minutes or until cake is cooked through. Transfer to a wire rack to cool.
Use a ruler and toothpicks to cut each cake into 7-by-13 inch rectangles. Round the edges using a paring knife. On one cake use a straw to punch holes 5 across and 15 down on the cake.
Lay out plastic wrap large enough to wrap the entire cake. Place the bottom of the cake down on the plastic wrap. Use food-safe scissors to cut open the rectangular ice cream cartons and lay the ice cream down on the bottom of the cake. Cover with more plastic wrap and smooth down the sides until you form a block. Remove the plastic wrap and top with the second cake. Wrap the entire cake in plastic wrap and freeze for at least 2 hours before serving.