Preparation

• Make the reduced strawberry puree first, and let cool: In a blender or food processor, puree the fresh strawberries. You should have a little more than 1 cup (about 270g). Transfer the puree to a small saucepan over medium-low heat. Simmer, stirring occasionally, until it’s reduced to ½ cup (about 135g). This usually takes around 25–35 minutes. Remove from heat, pour into a heat-safe bowl, and cool completely before using.
• Preheat the oven to 350°F (177°C). Grease two 9-inch round cake pans, line with parchment paper rounds, then grease the parchment paper.
• Make the cake: In a medium bowl, whisk the cake flour, baking powder, baking soda, and salt together. Set aside.
• In a large bowl using a handheld or stand mixer fitted with a paddle attachment, beat the butter and sugar together on medium-high speed until light and creamy, about 3 minutes. Add the egg whites and beat on high speed until combined, about 2 minutes. Scrape down the sides of the bowl as needed. Add the sour cream and vanilla extract and beat on medium-high speed until combined, about 1 minute.
• Add the dry ingredients and then, with the mixer running on low speed, slowly pour in the milk and beat until just combined. Do not overmix. Whisk in the room-temperature reduced strawberry puree and food coloring (if using). The batter should be slightly thick. Pour the batter evenly into the prepared cake pans.
• Bake for 24–25 minutes or until a toothpick inserted in the center of the cake comes out clean. Cool the cakes in the pans set on a cooling rack for 1 hour. Run a knife around the edges to loosen the sides, remove the cakes from the pan, peel off the parchment, and place on the rack to finish cooling.
• Make the frosting: In a blender or food processor, process the freeze-dried strawberries into a fine powder. If any larger bits remain, sift the powder through a fine-mesh sieve. Set aside.
• In a large bowl using a handheld or stand mixer fitted with a paddle attachment, beat the cream cheese and butter on medium-high speed until smooth, about 2 minutes. Add the confectioners’ sugar, strawberry powder, milk, and vanilla. Beat on low speed for 30 seconds, then gradually increase to high speed and beat for 3 minutes until completely combined and creamy.
• Assemble and frost: Level the cakes using a large serrated knife, slice a thin layer off the tops of the cakes to create a flat surface. Place 1 cake layer on your cake stand, spread ¾–1 cup of frosting in an even layer on top. Top with the second layer, upside down, and spread 1 cup of frosting all over the top and sides in a very thin layer to make a crumb coat. Refrigerate the cake until the crumb coat has set, about 20 minutes. Cover the top and sides with the remaining frosting.
• Cover leftover cake tightly and store in the refrigerator for up to 5 days.