Instructions

1. Arrange a rack in the middle of the oven and heat the oven to 350°F. Line 2 (9-inch) round cake pans with parchment paper and lightly coat the paper and sides with cooking spray. Place on a rimmed baking sheet.
2. Place 1 3/4 cups granulated sugar, 1 1/2 cups buttermilk, 3/4 cup vegetable oil, 1 tablespoon vanilla extract, 1 tablespoon red food color, and 1 1/2 teaspoons kosher salt in a large bowl. Whisk until creamy and bright red.
3. Place 2 1/2 cups all-purpose flour and 1/3 cup Dutch-processed cocoa powder in a medium bowl and whisk to combine.
4. Add 1 1/4 teaspoons baking soda to the sugar mixture and whisk to combine. Immediately add the flour mixture and mix with a rubber spatula until it forms batter, about 10 seconds. (Some small lumps are OK, but there should be no visible white flour spots.) Divide the batter evenly between the cake pans.
5. Bake, still on the baking sheet, until the cakes are slightly domed, spring back when lightly pressed in the center, and a toothpick inserted in the centers comes out mostly clean with just a few crumbs, about 35 minutes.
6. Transfer the cake pans to a wire rack. Let the cakes cool in the pans for 15 minutes. Run an offset spatula or thin knife around the cake edges, then flip the cakes out onto the rack top side down. Let cool completely. Meanwhile, make the ice cream.
7. Place 8 ounces cold cream cheese and 1 can condensed milk in the bowl of a food processor fitted with the blade attachment. Process until well blended, about 1 minute.
8. Squeeze the juice from 1/2 medium lemon until you have 1 tablespoon. Add the lemon juice, 2 cups cold heavy cream, and 1 teaspoon vanilla extract to the food processor. Process until thick and the consistency of whipped cream, about 3 minutes. Transfer to a large bowl, cover with plastic wrap, and refrigerate until ready to use. Wash and dry the food processor.
9. When the cakes are cooled, flip them over. Trim the tops with a large serrated knife so the cakes are level. Transfer the scraps from the trimmed tops to the food processor. Pulse in 2-second intervals until fine crumbs form, 4 to 5 pulses. Add the crumbs to the ice cream base and gently fold until combined.
10. Line 1 (9-inch) round cake pan with plastic wrap, covering the bottom and the sides and allowing a 5-inch overhang on either side. (Alternatively, use 10-inch high acetate sheets the sides of the pan.)
11. Place 1 cake layer in the pan. Top with half of the ice cream mixture and spread into an even layer. Top with the second layer and remaining ice cream mixture. Cover with plastic wrap and freeze overnight.
12. If the freezer is set very cold and the cake is frozen solid, let the cake sit for 15 minutes at room temperature to soften slightly. Meanwhile, make the whipped cream frosting.
13. Place 1 cup cold heavy cream, 8 ounces cream cheese, 1/4 cup powdered sugar, and 1 teaspoon vanilla extract in the bowl of a food processor fitted with the blade attachment. Process until firm peaks form, stopping and scraping down the sides of the bowl every minute, about 4 minutes total.
14. Transfer the cake to a serving platter and unwrap. Frost all over with the whipped cream and decorate with sprinkles if desired. Slice and serve!