Strawberry Sheet Cake with Rhubarb Frosting

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This Strawberry Sheet Cake with Rhubarb Frosting is the perfect spring cake! A light and fluffy white cake is mixed with roasted strawberries then topped with a deliciously tart and smooth rhubarb frosting and sprinkles! It’s simple to make without any fancy ingredients or complex steps! Enjoy it with a Mint Vanilla Iced Coffee!

I don’t think there is anything I love more than sheet cake. It’s so simple to make for a crowd and it doesn’t require any special skills or tools. This Mini Strawberry Cake, Lemon Cake, and Carrot Sheet Cake are all crowd-pleasers and just as delicious and simple to make!

Ingredients You’ll Need for Strawberry Sheet Cake with Rhubarb Frosting

Rhubarb and strawberries – Roasting intensifies their natural flavors so this cake will really taste like strawberries and rhubarb! The roasted strawberries are blended and mixed into the cake batter and the rhubarb is blended and mixed into the frosting.

Red food coloring – Totally optional but it will give your cake and frosting a very pretty pink color.

Cake flour – A must for baking cakes. Cake flour has a low gluten content so it will make your baked goods light, very fluffy with a tender crumb.

Egg whites – You’ll need a lot of egg whites, 9 total! It’s used in both the cake batter and in the Swiss Meringue frosting. If you’ve never made this type of frosting before it’s pretty simple but it involves heating the sugar and egg whites over the stove before it’s whipped with a stand mixer with the rest of the ingredients.

For the rest of the ingredients, please refer to the recipe index card below!

How to Make This Strawberry Sheet Cake with Rhubarb Frosting

Roast the strawberries and rhubarb. Line a sheet pan with parchment paper, then place chopped strawberries on one side and rhubarb on the other. Sprinkle each with 2 tablespoons of sugar. Roast at 350 degrees for 10 minutes.

Blend. Allow the fruit to cool slightly then blend strawberries until smooth, add 3 drops of red food coloring if desired, then transfer to a bowl. Blend the rhubarb until smooth then transfer it to a separate bowl. Set aside.

For the cake. Combine dry ingredients together in a medium bowl then set aside. In the bowl of a stand mixer fitted with the paddle-attachment, cream butter and sugar together until light and fluffy. In a measuring cup whisk together milk, egg whites, vanilla, and strawberry puree. Alternate adding in wet ingredients and dry ingredients to the butter/sugar mixture until you have a smooth batter and everything is combined.

Bake. Pour cake batter into a prepared baking pan to bake for 25 minutes or until a toothpick inserted in the middle comes out clean. Allow the cake to cool for 5 minutes then invert it and allow it to cool to room temperature.

For the frosting. Place the bowl of a stand mixer over a simmering pot of water. Add sugar and egg whites, heat until the sugar has dissolved. Transfer the bowl to the stand mixer then beat for 5-7 minutes or until fluffy. Next beat in butter until smooth and glossy, finally pour in the rhubarb puree and red food coloring, mixing until combined.

Decorate. Spread frosting evenly over the cake then top with sprinkles.

Tips and Tricks

If your Swiss Meringue frosting curdles when you add the puree. Remove 1/4 cup (you can eyeball this measurement) of the frosting and microwave it for about 30 seconds OR set it over a double-boiler until it’s very smooth and melted. With the mixer running, slowly pour in the melted frosting. Beat for an additional two minutes. The frosting will magically come together and become fluffy and cohesive!

If you’re frosting is soupy, stick it in the fridge for about 5 to 10 minutes and then beat it for 1 to 2 minutes. It should stiffen up a bit.

If rhubarb is out of season, you can replace it with strawberry puree. I would double the amount of strawberries and then use the exact same measurement of puree for the frosting (1/4 cup of strawberry puree).

Recipe FAQs

Can I make it into a regular cake? Totally! Instead of using a 13×9-inch sheet pan pour the cake batter into two 9-inch round cake pans. Check on the cake around the 20 minute mark. Can I make this cake into cupcakes? Absolutely! This cake will make about 24 cupcakes. They’ll bake for a shorter amount of time, so I would check on them around the 15 minute mark.

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Roasted Strawberries + Rhubarb:Rhubarb Swiss Meringue Frosting:
To Make the Roasted Strawberries + Rhubarb:Preheat the oven to 350 degrees F. Add the sliced strawberries to one side of a parchment-lined baking sheet and the diced rhubarb to the other side. Sprinkle about 2 tablespoons of sugar onto the strawberries and sprinkle the remaining 2 tablespoons of sugar onto the rhubarb. Toss them gently and keeping them separate, transfer them to the oven to roast for 10 minutes.Remove and allow them to cool for about 5 to 10 minutes. Add the strawberries to a blender and pulse until smooth. (You should end up with about 1/2 cup puree. Mix in 3 drops of food coloring, if you like.) Next, add the rhubarb to the blender and pulse until smooth.To Make the Sheet Cake:Keep the oven at 350 degrees F (as it was for roasting the strawberries). And grease a 13×9-inch baking pan. Set aside.In a medium bowl, add the cake flour, baking powder and salt. Whisk until combined. Set aside.To the bowl of a stand-up mixer with the paddle attachment, add the butter and sugar. Beat until light and fluffy, about 2 to 3 minutes. In a measuring cup, pour in the milk, egg whites, vanilla extract or paste and reserved 1/2 cup strawberry puree (discard any extra) and whisk until combined.Turn the mixer to low speed and, alternating between the dry ingredients and the liquid ingredients (the strawberry/egg white mixture), add the them butter/sugar mixture until the batter is relatively smooth.Pour the batter into the prepared baking pan and transfer to the oven to bake for 25 minutes, until a skewer inserted into the center comes out clean.Allow the cake to cool in the pan for about 5 minutes and then invert onto a cooling rack and cool to room temperature. It’ll probably take a good hour.To make the frosting:Bring a saucepan filled with a few inches of water. Place the clean bowl of a stand-up mixer atop the saucepan. Add the sugar and egg whites to the bowl and mix.Heat the mixture until it reaches 140 degrees F or until the sugar has dissolved completely. Carefully (it’ll be hot!) transfer the bowl to the stand-up mixer and with the whisk attachment, beat for 5 to 7 minutes, until very fluffy. Remove the whisk attachment and replace with the paddle attachment. With the mixer running on low speed, add the butter, one cube at a time until smooth and glossy. Lastly, pour in the rhubarb puree and red food coloring and mix until combined.To Decorate the Cake:When the cake is completely cool, pour the frosting on top of the cake. Using an offset spatula or any spatula you own, smooth it out until it reaches the edges. Make a few swoops in the frosting so it looks cute. And then top it with a bunch of sprinkles!

Tips and Tricks

If your Swiss Meringue frosting curdles when you add the puree. Remove 1/4 cup (you can eyeball this measurement) of the frosting and microwave it for about 30 seconds OR set it over a double-boiler until it’s very smooth and melted. With the mixer running, slowly pour in the melted frosting. Beat for an additional two minutes. The frosting will magically come together and become fluffy and cohesive!

If you’re frosting is soupy, stick it in the fridge for about 5 to 10 minutes and then beat it for 1 to 2 minutes. It should stiffen up a bit.

If rhubarb is out of season, you can replace it with strawberry puree. I would double the amount of strawberries and then use the exact same measurement of puree for the frosting (1/4 cup of strawberry puree).

Calories: 585kcal | Carbohydrates: 70g | Protein: 7g | Fat: 32g | Saturated Fat: 20g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 8g | Trans Fat: 1g | Cholesterol: 83mg | Sodium: 244mg | Potassium: 249mg | Fiber: 1g | Sugar: 48g | Vitamin A: 984IU | Vitamin C: 15mg | Calcium: 83mg | Iron: 0.5mgNutrition information is automatically calculated, so should only be used as an approximation.

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