1. Prepare the cake according to the box directions, adding natural food color to one or both cakes if desired. Bake in two 8- or 9-inch round pans.
2. While the cakes bake, prepare a spot in your freezer to hold the completed cake.
3. When the cakes are baked, let them cool in the pans for 10 minutes, then transfer them to a cooling rack. Take the pints of ice cream out of the freezer.
4. Wipe one of the cake pans clean and allow it to cool completely before cutting a round piece of parchment to fit the bottom of the pan and two pieces of parchment ½-inch thick by 13-inches long. Once the pan is cool, lay the two long strips in an X and then place the round parchment over them. Alternatively, line the baking pan with plastic wrap that overhangs the sides by a couple inches.
5. When the ice cream has softened, put both pints in a large bowl and use a large spoon to mash it until it is uniformly soft and spreadable (it should not be runny). If using vanilla, add natural food coloring and/or sprinkles now if desired. Spread the ice cream into the prepared pan, making sure to spread it all the way to the edges. Transfer the ice cream to the freezer for at least one hour. Put the bowl and the beater you will use to whip the cream later in the freezer too.
6. Just before you are ready to put the cake together, whip the heavy cream with a handheld or stand mixer in the chilled bowl until soft peaks begin to form. Add the powdered sugar, to taste, and the vanilla extract and whip until stiff peaks form. You can also add natural food coloring to some or all of the whipped cream if desired. Transfer to the refrigerator.
7. Place one of the cake rounds on a serving plate large enough to hold the cake. Remove the pan with the ice cream from the freezer and run a thin spatula around the edge to loosen it. Use the overhanging parchment to pull the ice cream up and out of the pan. Carefully flip the frozen ice cream onto your hand then gently place it on top of the cake. Place the remaining cake on top of the ice cream and straighten it if necessary. Frost the cake with the whipped cream—you’ll need to work quickly to prevent the cake from melting. If at any point your cake seems to be softening, transfer the whole thing to the freezer for 20 minutes before proceeding. Use any leftover whipped cream to pipe decorations on top or dollop on top of slices just before serving. Sprinkle optional toppings over the top and freeze for at least 30 minutes before serving.
8. To serve, use a sharp chef’s knife to cut pieces and serve immediately. If the cake feels too hard to cut, allow it to sit at room temperature for a few minutes to soften slightly. Store any leftovers tightly wrapped in the freezer for up to one month.

Dairy-free version:

For the cake, replace the butter with Natural Grocers Brand Organic Extra Virgin Coconut Oil and omit the olive oil. Use unsweetened dairy-free milk in place of the milk. Choose your favorite dairy-free ice cream and replace the heavy whipping cream, powdered sugar, and 1½ teaspoons vanilla with two (9-ounce) tubs of coconut whipped topping. You will need to transfer the topping to the refrigerator about 2-4 hours before you are ready to put the cake together.