Step 1: Prepare the Strawberry Puree
Puree the Strawberries: Blend 1 pound of hulled strawberries until smooth, yielding just over 1 cup.
Reduce the Puree: In a medium saucepan over medium-low heat, simmer the puree while stirring occasionally. Reduce the mixture until you have about 1/2 cup (135g). This process takes 25-35 minutes, depending on the strawberries’ water content.
Cool Completely: Let the reduced puree cool entirely before using in the batter. For convenience, prepare it a day ahead and refrigerate it overnight.
Step 2: Preheat the Oven
Preheat the oven to 350°F (177°C).
Grease two 9-inch round cake pans and line them with parchment paper for easy release.
Step 3: Mix Dry Ingredients
In a medium bowl, whisk together the cake flour, baking powder, baking soda, and salt.
Set aside.
Step 4: Cream Butter and Sugar
Using a stand or handheld mixer fitted with a paddle attachment, beat the butter and sugar on high speed until light and fluffy (about 2 minutes).
Scrape down the bowl as needed.
Step 5: Add Wet Ingredients
Beat in the egg whites one at a time until fully combined.
Mix in the sour cream and vanilla extract, ensuring everything is incorporated.
Step 6: Combine Wet and Dry Mixtures
With the mixer on low speed, gradually add the dry ingredients to the wet mixture until just combined.
Slowly pour in the milk and mix gently.
Fold in the reduced strawberry puree and food coloring (if using) until evenly mixed. Avoid overmixing.
Step 7: Bake the Cake
Divide the batter evenly between the prepared pans.
Bake for 24-25 minutes, or until a toothpick inserted into the center comes out clean.
Let the cakes cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.
Step 8: Prepare the Frosting
Blend Strawberries: Process the freeze-dried strawberries in a food processor until they form a fine powder.
Cream Butter and Cream Cheese: Beat the cream cheese on high speed until smooth, then add the butter and mix until creamy.
Incorporate Dry Ingredients: Gradually add the powdered sugar, strawberry powder, 1 tablespoon of milk, and vanilla extract. Mix on medium-high speed until smooth.
Adjust Consistency: Add more milk if needed and a pinch of salt to balance the sweetness.
Step 9: Assemble the Cake
Level the cake layers with a serrated knife if necessary.
Place one layer on a serving plate and spread an even layer of frosting on top.
Add the second layer and frost the top and sides of the cake.
Refrigerate the cake for at least 45 minutes before slicing to ensure it holds its shape.
Step 10: Serve and Store
Serve chilled or at room temperature.
Store leftover cake in the refrigerator for up to 5 days in an airtight container.