1. Preheat oven to 350°F (176°C). Prepare an 8 inch cake pan with a circle of parchment paper in the bottom and grease the sides.
2. To make the cake batter, beat the sugar and butter together until light in color and fluffy, 3-4 minutes. Don’t skimp on the creaming.
3. Add the sour cream and vanilla extract and mix until well incorporated.
4. Add the egg whites and mix until well combined.
5. Combine the flour and baking powder in a separate bowl, then add half of the dry ingredients to batter and mix until well combined.
6. Add the milk and water and mix until well combined.
7. Add the remaining dry ingredients and mix until well combined.
8. Spread the cake batter evenly into the bottom of the prepared pan.
9. Bake for 18-20 minutes, or until a toothpick inserted comes out with a few crumbs. Set the cake aside to cool.
10. When the cake has cooled, lined two 8 inch cake pans with clear wrap that covers the bottom and sides of the pans.
11. Remove the dome from the top of the blue cake layer, then place it in the bottom of one of the cake pans.
12. Soften the cartons of ice cream. I let mine sit out for about 15-20 minutes, then added all but about a quarter of the ice cream to a large bowl. Use a rubber spatula to stir it well until it all comes together to a consistency similar to soft serve ice cream. Add half of the ice cream to another bowl and set it in the freezer for a few minutes while you work with the other half.
13. Add the white vanilla ice cream to the top of the blue cake layer and spread into an even layer. Set the cake/ice cream in the freezer to freeze completely.
14. Remove the remaining half of the vanilla ice cream from the freezer and color it with red gel icing color.
15. Add the ice cream to the other prepared cake pan and spread into an even layer. Freeze until firm.
16. Once both ice cream layers are firm, remove the blue cake layer/white ice cream from its pan and place on a cardboard cake circle or serving platter. Keep in mind that it will need to fit in your freezer.
17. Remove the red layer from it’s pan and set on top of the white ice cream layer. Place cake back in the freezer.
18. To make the whipped cream, add the heavy whipping cream, powdered sugar and vanilla extract to a large mixer bowl. Whip on high speed until stiff peaks form.
19. Frost the outside of the cake with the whipped cream, leaving about 1/3 of a cup or so leftover.
20. Place the cake in the freezer for about 10-15 minutes so it stays firm. Color the remaining whipped cream with the red gel icing color.
21. Press your sprinkles onto the sides of the cake, then pipe swirls of the red whipped cream around the top edge. Freeze cake until ready to serve.