Description

This Strawberry Sheet Cake with Rhubarb Swiss Meringue Frosting is a delightful dessert featuring a moist, tender cake infused with roasted strawberry puree and topped with a luscious rhubarb-flavored Swiss meringue frosting. The cake is baked in a 13x9-inch pan, combining the natural tartness of rhubarb with the sweet, rich flavors of strawberries and creamy butter, making it perfect for gatherings or special occasions.

Ingredients

Roasted Strawberries and Rhubarb

2 cups sliced strawberries (from 1/2 pound strawberries)
1/4 cup white granulated sugar (divided into 2 tablespoons each)
1 cup diced rhubarb (from 4 to 5 shortish stalks)

Sheet Cake

2 3/4 cups cake flour (plus more for dusting pans)
2 1/2 teaspoons baking powder
1 teaspoon salt
1 cup unsalted butter
1 3/4 cups white granulated sugar
3/4 cup milk
6 large egg whites
2 teaspoons pure vanilla extract or 1/4 teaspoon vanilla paste
3 drops red food coloring (optional, for strawberry puree)

Rhubarb Swiss Meringue Frosting

3 large egg whites
3/4 cup white granulated sugar
1 cup unsalted butter (at room temperature)
1/4 cup rhubarb puree
2 to 3 drops red food coloring (optional)

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Instructions

Roast the Strawberries and Rhubarb: Preheat your oven to 350°F. Spread sliced strawberries on one side and diced rhubarb on the other side of a parchment-lined baking sheet. Sprinkle about 2 tablespoons of sugar over the strawberries and 2 tablespoons over the rhubarb. Toss gently to coat and roast separately for 10 minutes. Remove from oven and cool for 5 to 10 minutes.
Make Purees: Transfer the roasted strawberries to a blender and pulse until smooth, yielding about 1/2 cup puree. Add red food coloring drops if desired. Next, blend the roasted rhubarb until smooth to create the rhubarb puree.
Prepare Cake Batter: Keep the oven at 350°F. Grease a 13x9-inch baking pan and set aside. In a bowl, whisk together the cake flour, baking powder, and salt. In a stand mixer with the paddle attachment, beat butter and sugar until light and fluffy, about 2 to 3 minutes. In a separate cup, whisk milk, 6 egg whites, vanilla, and the strawberry puree.
Combine Ingredients: On low mixer speed, alternately add the dry ingredients and the milk mixture to the butter and sugar mixture, mixing just until smooth and combined.
Bake the Cake: Pour batter into the prepared pan. Bake for 25 minutes or until a toothpick inserted in the center comes out clean. Let cool in the pan for 5 minutes, then invert onto a wire rack and cool completely, about 1 hour.
Make Swiss Meringue Frosting: Set a saucepan with simmering water. Place a clean mixer bowl over the saucepan and add 3 egg whites and sugar. Heat while mixing until the mixture reaches 140°F and sugar is dissolved.
Whip Meringue: Transfer the hot bowl to a stand mixer with a whisk attachment and beat on medium-high speed for 5 to 7 minutes until fluffy and glossy. Replace whisk with paddle attachment. On low speed, add butter piece by piece until smooth and shiny.
Incorporate Rhubarb Puree: Add the rhubarb puree and optional red food coloring to the frosting and mix until fully combined.
Frost the Cake: Once the cake is completely cooled, spread the frosting evenly over the top using an offset spatula. Create decorative swoops and top with sprinkles as desired.

Notes

Roasting the strawberries and rhubarb enhances their natural flavors and sweetness.
Using cake flour ensures a tender and delicate crumb.
Ensure the egg whites and sugar mixture reaches 140°F to properly dissolve sugar for Swiss meringue.
The rhubarb puree adds a subtle tartness and unique flavor to the frosting.
Red food coloring is optional and meant to enhance the vibrant color of the puree and frosting.
Butter should be at room temperature for easy incorporation into the frosting.
Use an offset spatula for smooth and professional-looking frosting application.