Sandwich Cookie Ice Cream Cake

Ingredients:

• 1 (450-500 gram) box chocolate sponge cake mix (plus required ingredients)
• 1 large egg
• 3 rectangular cartons of vanilla ice cream, 1420 ml, softened

Preparation:

1. Preheat oven to 350°F (180°C). Spray two 12 x 17-inch (30 x 43 cm) rimmed baking sheets with cooking spray, then line with parchment paper, leaving the paper overhanging the short edges.
2. Prepare the sponge cake mixture, using one extra egg. Divide the batter between two baking sheets; smooth the batter with a spatula. Bake until set, 8-9 minutes; let cool.
3. Measure 6 cm (2.5 in) of cake from each long side of one cake; mark with toothpicks. Measure with a ruler, then remove the toothpicks and cut along the marked line so that the cake is 18 cm (7.3 in) wide.
4. Round the corners of the cake with a knife. Use a straw to make holes (4 across and 10 down). Trim the other cake (no need to make holes). Freeze the cakes for 30 minutes.
5. Invert the cake layer onto a clean baking sheet; remove the parchment paper. Open 1 carton of ice cream with kitchen scissors, then invert the ice cream onto the cake.
6. Repeat with the other two ice cream boxes, layering them one after the other onto the crust. Wrap in plastic wrap and press down with your hands to smooth the ice cream and fill in any empty spaces.
7. Using a thin spatula, remove the other cake layer from the parchment paper and place it on top of the ice cream. Trim off any excess cake and smooth out the sides. Freeze the ice cream cake for at least 2 hours before serving.