Strawberry Lemonade Cake

Place strawberries, sugar, and lemon juice for reduction into an electric blender and purée until smooth.

Pour strawberry mixture into a large saucepan and simmer over medium heat, stirring frequently, until reduced by half, 20 to 25 minutes. Remove from heat and let cool to room temperature, 10 to 15 minutes. Reserve 1/2 cup plus 5 tablespoons for cake and frosting; remainder will be used as cake filling.

Preheat the oven to 350 degrees F (175 degrees C). Grease two 9-inch cake pans and line with parchment paper.

Whisk flour, baking soda, baking powder, and salt together in a medium bowl. Set aside.

Beat sugar and butter using an electric mixer in a large bowl until creamy. Beat in eggs one at a time, mixing thoroughly after each addition. Mix in lemon zest and vanilla extract. Stir in 1/3 of flour mixture until just combined. Stir in 1/2 of the sour cream, and 1/2 of the lemon juice. Repeat alternating additions of flour mixture and sour cream plus lemon juice until just combined, making sure not to overmix.

Place 1/2 of the batter into a separate bowl. Fold in 1/2 cup strawberry reduction. Place dollops of both lemon and strawberry-lemon batters alternately into the prepared cake pans. Swirl batters together with a butter knife.

Bake in the preheated oven until a toothpick inserted into center of each cake comes out clean, 30 to 35 minutes. Remove from the oven and let cool for 10 minutes in the pans before removing and transferring cakes to a wire rack to cool completely, 15 to 30 minutes.

While cakes are cooling, beat butter for frosting with an electric mixer in a mixing bowl until light and fluffy. Beat in powdered sugar 1 cup at a time until incorporated. Mix in 5 tablespoons strawberry reduction, lemon juice, vanilla extract, lemon zest, and salt until combined. Pour in heavy cream and beat until frosting is smooth and fluffy, 2 to 3 minutes. Add additional powdered sugar if too thin, or additional heavy cream if too thick, 1 tablespoon at a time, until desired consistency is reached.

Place 1 cooled cake layer on a serving platter and cover top with a thin layer of frosting. Pipe a border around the edge of the cake layer using a piping bag filled with frosting, leaving the center open. Pour remaining strawberry reduction into the center of the border, making sure it doesn't overflow over the sides. Place second cake layer on top and continue to frost as desired. Keep refrigerated until ready to serve.