1-Making the Strawberry Reduction: Add hulled strawberries and lemon juice to a saucepan over medium heat.

2-Making the Strawberry Reduction: Heat for a few minutes, then mash the strawberries with a fork or potato masher.

3-Making the Strawberry Reduction: Let the mixture simmer for about 10 minutes, stirring occasionally.

4-Making the Strawberry Reduction: Strain the mixture into a bowl through a fine-mesh sieve to remove seeds.

5-Making the Strawberry Reduction: Cover the bowl and chill the reduction in the refrigerator for 10-15 minutes before using.

6-Preparing the Cake: Preheat your oven to 350°F (175°C) and prepare three 6-inch cake pans by buttering and flouring them.

7-Preparing the Cake: In a large bowl, sift together the dry ingredients (1 2/3 cups all-purpose flour, 1 cup granulated sugar, 1/4 teaspoon heaping baking soda, and 1 teaspoon heaping baking powder).

8-Preparing the Cake: In a separate bowl, mix the wet ingredients (3/4 cup unsalted butter at room temperature, 3 egg whites, 1/2 cup sour cream or yogurt, and 1/2 cup milk) until just combined.

9-Preparing the Cake: Divide the batter evenly into three bowls.

10-Preparing the Cake: Add 2 tablespoons cocoa powder to one bowl and mix well to create the chocolate layer.

11-Preparing the Cake: Add 3/4 of the strawberry reduction to the second bowl and mix to create the strawberry layer.

12-Preparing the Cake: Leave the third bowl as is for the vanilla layer.

13-Baking the Layers: Pour the chocolate batter into one prepared pan. Bake for about 30 minutes or until a toothpick inserted comes out clean.

14-Baking the Layers: Bake the vanilla layer next, which may take slightly longer than the chocolate layer.

15-Baking the Layers: Bake the strawberry layer for 5-8 minutes longer than the vanilla layer. Test with a toothpick for doneness.

16-Baking the Layers: Promptly remove each layer from the oven when done and let cool in the pans for a few minutes before transferring to a wire rack to cool completely.

17-Preparing the Buttercreams: In a stand mixer with the paddle attachment, whip 1 cup unsalted butter (room temperature) for about 5 minutes until light and fluffy.

18-Preparing the Buttercreams: Slowly beat in 3 pounds confectioners sugar, mixing on low speed initially to prevent a sugar cloud.

19-Preparing the Buttercreams: Add 2 tablespoons vanilla extract and a splash of whole milk. Beat until smooth and fluffy.

20-Preparing the Buttercreams: Divide the buttercream evenly into three parts.

21-Preparing the Buttercreams: Keep one part as is for the vanilla buttercream.

22-Preparing the Buttercreams: Mix 1/4 cup cocoa powder into the second part to create the chocolate buttercream.

23-Preparing the Buttercreams: Mix the remaining strawberry reduction and optionally a few drops of pink food coloring into the final part for strawberry buttercream.

24-Preparing the Buttercreams: Transfer each buttercream to separate piping bags with tips snipped off.