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), ensuring there are no lumps. Pour the batter evenly into the prepared cake pans.

Bake for 24–25 minutes or until a toothpick inserted into the center of the cake comes out clean. Cool the cakes in the pans on a cooling rack for 1 hour.

Run a knife around the edges to loosen the sides, remove the cakes from the pans, peel off the parchment, and place on the rack to finish cooling. The cakes must be completely cool before frosting and assembling.

Make the frosting: In a blender or food processor, process the freeze-dried strawberries into a fine powder. 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. Place 1 cake layer on your cake stand or serving plate. Spread ¾–1 cup of frosting in an even layer on top. Top with the second layer and spread 1 cup of frosting all over.

Refrigerate the cake until the crumb coat has set, about 20 minutes. Cover with the remaining frosting. Refrigerate the cake for at least 20 minutes before slicing to help it keep its shape.