STARS-AND-STRIPES CAKE

Steps:

• Make the cake: Preheat the oven to 350 degrees F. Coat a 13-by-18-inch rimmed baking sheet with cooking spray; line with parchment, then spray the parchment. In a medium bowl, whisk the flour with the cocoa powder and baking powder. Set aside.
• Beat the egg whites with a mixer on high speed until foamy. Beat in the cream of tartar and salt, then slowly beat in 1/2 cup granulated sugar. Increase the speed to high; beat until stiff shiny peaks form, 2 to 3 minutes. Transfer the meringue to a separate bowl.
• In the same mixer bowl (leave it dirty!), combine the egg yolks, vanilla and the remaining 1/2 cup granulated sugar. Beat on high speed until light and doubled in volume, about 2 minutes. Beat in the water and canola oil.
• Sift the flour mixture into the egg yolk mixture, then stir with a rubber spatula until just combined.
• Add the food coloring to the batter and beat on high speed until smooth and bright red, about 1 minute.
• Stir a dollop of the meringue into the batter using a rubber spatula. Add the remaining meringue and gently fold into the batter until no white streaks remain.
• Transfer the batter to the prepared baking sheet; spread evenly with an offset spatula. Tap the bottom of the pan firmly against the counter to remove any air bubbles.
• Bake until a toothpick inserted into the center of the cake comes out clean, 15 to 20 minutes. Immediately loosen the edges with a paring knife.
• Dust the cake with confectioners' sugar, working quickly while the cake is still warm.
• Lay a clean kitchen towel (not terry cloth) over the cake. Place another baking sheet on top of the towel.
• Invert the cake onto the towel. Remove the pan and peel off the parchment.
• Starting at a short end, roll up the cake and towel together into a log. Keep the cake rolled up until it has cooled completely.
• Unroll the cake (it's OK if the end is still curled up). Cut the cake into 3 long strips, each about 4 inches wide. Use a ruler to make sure they're even.
• Spread an even layer of frosting on each strip of cake (use a little less than one-third of the frosting). Make sure to get frosting under the curled end.
• Make the frosting: In a clean mixer bowl, beat the cream cheese and confectioners' sugar on medium-high speed until smooth, about 2 minutes. With the mixer on low speed, add the vanilla and heavy cream. Slowly increase the speed to high and beat until smooth.
• Roll up one of the strips into a tight spiral.
• Move the spiral over to the next strip so that the ends meet and roll up into a fatter spiral. Continue with the third strip to make a large spiral.
• Turn the cake flat-side down and place on a cardboard round or platter. Gently squeeze the spiral together to make sure it's compact.
• Cover the cake completely with a thin layer of frosting, using the frosting to cover the seam of the spiral. Refrigerate 30 minutes.
• Return the cake (without the cardboard round) to your workspace and cover completely with the remaining frosting using an offset spatula.
• Place a star-shaped cookie cutter on top of the cake. Sprinkle some blue sanding sugar inside the cutter (use a small brush to help distribute the sugar), then carefully lift the cutter. Repeat to make more stars in different sizes. Refrigerate until ready to serve.
• When you slice into the spiral, you see vertical stripes!