A tender, springy white cake infused with intensely reduced fresh-strawberry puree, finished with a silky strawberry cream cheese frosting made from real freeze-dried strawberries for bright, authentic berry flavor.
Make the reduced strawberry puree: In a blender or food processor, puree the fresh strawberries (a little over 1 cup / about 270g). Transfer to a small saucepan and simmer over medium-low heat, stirring occasionally, until reduced to 1/2 cup (about 135g), 25–35 minutes. Remove from heat and cool completely. Cover and refrigerate overnight if desired; bring to room temperature 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.
Make the cake batter—dry ingredients: In a medium bowl, whisk together cake flour, baking powder, baking soda, and salt; set aside.
Cream butter and sugar: Using a handheld or stand mixer fitted with a paddle, beat the butter and granulated sugar on medium-high speed until light and creamy, about 3 minutes.
Add egg whites: Beat in the egg whites on high speed until combined, about 2 minutes; scrape down the bowl as needed.
Add sour cream and vanilla: Beat in sour cream (or Greek yogurt) and vanilla on medium-high until combined, about 1 minute.
Combine dry and wet: Add the dry ingredients, then with the mixer running on low, slowly pour in the milk and mix just until combined. Do not overmix.
Add strawberry puree: Whisk in the room-temperature reduced strawberry puree and, if desired, 1–2 drops of red or pink food coloring. Batter will be slightly thick.
Bake: Divide batter evenly between prepared pans and bake 24–25 minutes, or until a toothpick inserted in the center comes out clean.
Cool: Cool cakes in pans on a wire rack for 1 hour. Run a knife around edges, remove from pans, peel off parchment, and cool completely.
Make the strawberry cream cheese frosting: Grind freeze-dried strawberries into a fine powder in a food processor or blender. In a large bowl, beat cream cheese and butter together until smooth. Add confectioners’ sugar, milk, vanilla, and a pinch of salt; beat until creamy. Mix in the strawberry powder until evenly pink and fluffy.
Assemble: Place one cake layer on a serving plate, spread frosting over the top, then add the second layer. Apply a thin crumb coat if desired, then frost the top and sides. Slice and serve.