Preheat your oven according to the package instructions for the chocolate cake mix. Prepare the cake batter and pour it into two 9-inch round cake pans. Bake for 25-30 minutes until a toothpick comes out clean. Cool in pans for 10 minutes before transferring to a wire rack.

While the cakes cool, let the chocolate chip cookie dough ice cream sit at room temperature for 10-15 minutes until it's spreadable.

Place one cake layer on a freezer-safe plate. Secure wax paper around the edge. Spread half of the softened ice cream over the cake and sprinkle 2/3 of the crushed cookies on top.

Place the second cake layer on top of the ice cream and press down gently. Freeze the assembled cake for 2-3 hours until set.

To make the chocolate sauce, combine chocolate chips and butter in a saucepan. Heat over medium-low, stirring until melted and smooth, about 5-7 minutes. Remove from heat and cool slightly.

After freezing, remove the cake from the freezer and take off the wax paper. Drizzle the warm chocolate sauce over the top and garnish with the remaining crushed cookies before serving.