Strawberry Lemonade Sheet Cake

Preheat the oven to 350°F. Generously coat a 13- x 9-inch baking pan with cooking spray.

Process freeze-dried strawberries in a food processor until powdery, about 15 seconds. Set aside until ready to use.

In a medium bowl, whisk together the cake flour, baking powder, baking soda, and salt. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, sugar, and oil together until lightened in color and the butter has fully incorporated, about 5 minutes. Use a spatula to ensure everything is combined. Add the egg whites, lemon zest, and vanilla extract and mix until combined.

Alternating between the buttermilk and the dry ingredients, starting with the dry ingredients, add a little at a time and mix just until the ingredients are incorporated. End with the dry ingredients and stop mixing right before the ingredients are combined. Pour in the freeze-dried strawberries and mix until just combined. Add the red food coloring, if using, and mix until incorporated.

Carefully batter pour into prepared pan. Bake for 25 - to 27 minutes, or until a cake tester comes out clean in the center. Set aside and let cool fully.

Prepare frosting: in the bowl of a stand mixer with a whisk attachment, whip the butter until it reaches a mayonnaise-like consistency, about 5 minutes.

Add powdered sugar, salt, lemon zest, lemon juice, and cream to the butter, mixing slowly until incorporated. Increase the speed to medium-high and mix until it has increased in volume, about 3 minutes. Taste the frosting to ensure it isn’t too sweet. If needed, add a small pinch of salt and mix to combine.

Spread the frosting onto the cooled cake in an even layer. Garnish with sliced strawberries and lemons, if using.