What’s the most delicious – and prettiest – summer cake of all? Of course we’re partial, but we’re going to go with White Cake with Rhubarb Curd.
This cake is moist and fluffy, and the sweet-tangy rhubarb layer really lifts it over the top. It’s perfect for a light luncheon, and it’s formal enough for a fancy summer dinner.
What Is Rhubarb? What Is Rhubarb Curd?
To answer the question, “What is Rhubarb?” we’d first point you to our Rhubarb 101 article. In short, rhubarb is a perennial plant that grows celery-like stalks that range from green to deep red. (The leaves are toxic, which is why stores and markets only sell the trimmed stalks). It’s not a fruit, although it’s most often prepared like one. It looks like red celery, and in fact, if you eat it raw, it tastes like a tart celery.
Most people make a basic rhubarb sauce it by stewing it with sugar. Once it’s cooked, rhubarb sauce tastes a lot like a tangy applesauce.
Rhubarb curd, on the other hand, is similar to other fruit curds (such as lemon curd). It’s made with egg yolks to give it a little more “heft.” Once cooked, it’s thick and even spreadable…But it still has that delicious tangy-sweet taste.
How Do You Make a Rhubarb Curd Cake?
To make a rhubarb curd cake, you simply use rhubarb curd as the “frosting” in between the cake layers.
Rhubarb curd is by definition thicker than a rhubarb sauce. But to make it hold together as a layer in this cake, we had to make it even a little bit thicker than usual. To make sure that the rhubarb curd would be thick enough, we added a smidge of corn starch. That helped create a sturdy enough foundation to hold cake layers in place.
To test whether our rhubarb curd was thick enough while we were cooking, we did the spatula test. If you can draw a line through the pan and it separates the curd (like the Red Sea), then it’s good.
White Cake With Rhubarb Curd Recipe
White Cake with Rhubarb Curd
A pretty summer cake made with layers of white cake, alternating with layers of sweet and tangy rhubarb curd.
Ingredients
For the cake
- 1 box white cake mix (we used Betty Crocker Super Moist White Cake Mix)
- 1 cup whole milk
- 1/2 cup butter, melted
- 3 egg whites
For the rhubarb curd
- 1 pound fresh rhubarb, cut into slices
- 1/4 cup fresh raspberries
- 1/4 cup water
- 1/2 cup sugar
- juice of 1/2 lemon
- 3 egg yolks
- 1 tsp corn starch
For the frosting
- 8 ounces cream cheese
- 1/4 cup butter
- 1 1/2 cups powdered sugar
- 1 tsp vanilla extract
For the garnish
- raspberries
- mint leaves
- assorted edible flowers
Instructions
For the cake
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In a large mixing bowl, combine the cake mix, milk, melted butter, and egg whites. Using an electric beater, beat on medium high for two minutes.
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Add 1/3 of the batter to a greased 8-inch springform pan. (If you have more than one pan, you can bake all three layers at once. Otherwise, bake one at a time, making three layers altogether. Bake at 350 degrees for 25 to 28 minutes, or until light golden brown on top. A cake tester should come out clean. Set the cake layers aside to cool on a cooling rack.
For the rhubarb curd
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Combine the chopped rhubarb, raspberries, water, sugar, and lemon juice in a medium saucepan. Heat over medium-high heat until boiling, reduce to a simmer and simmer gently for 10 to 15 minutes, or until rhubarb is soft.
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Remove rhubarb mixture from heat and blend in a blender or food processor. Return the mixture to the saucepan, reserving about 1/3 to 1/2 cup of the mixture to set aside.
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Combine the reserved mixture with the egg yolks and the corn starch; whisk together thoroughly.
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Begin heating the mixture in the saucepan until it again comes to a boil. Reduce heat to a simmer. Slowly add the rhubarb/egg yolk mixture in with the rhubarb in the saucepan, whisking constantly for 2-3 minutes so that no lumps form. Continue simmering for about 10 minutes, stirring frequently, until the mixture is reduced and thick. Remove from heat and set aside to cool. Chill for several hours before using on the cake.
For the frosting
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In a medium mixing bowl, mix together the cream cheese, butter, powdered sugar, and vanilla until smooth and creamy. Set aside.
To assemble the cake
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Have the (cooled) cake layers, the (chilled) rhubarb curd, and the cream cheese frosting all ready and at hand. Trim two of the three cake layers, if necessary, so that they are completely flat on top.
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Place the first cake layer on desired cake plate. Spread a 1/2 inch thick layer of rhubarb curd on top. Place the second cake layer on top, and repeat, spreading with another layer of rhubarb curd. Place the final layer on top, and spread with cream cheese frosting. Decorate with raspberries, mint leaves, and edible flowers. Serve immediately, if possible, or else chill until ready to serve. Serves 10.
OK – got all that? It’s really not as complicated as it sounds! Once you have all of the layers made, the real fun is in putting it all together.
Just a few notes: One, we added raspberries to this rhubarb curd to make sure that it had some “extra” red coloring. If you already have very red rhubarb, you don’t need the raspberries. We’ve seen some recipes that call for a drop of red food coloring, but we prefer to avoid that if possible.
Two, we doctored up the cake mix a little bit to make it richer and more bakery-like. (While one of our taste-testers was eating the cake, he said, “Make sure to tell people how good the cake is.”)
Three, yes, we know it’s a pain to separate eggs. And no one likes having a bunch of egg yolks or egg whites left over. That’s the magic of this recipe… It uses the exact same number of egg yolks and egg whites. It’s a compulsive person’s dream!
And last, just a warning: The rhubarb curd is not built to be a long-term structural material. In other words, it’s not super-sturdy. It’s important to either serve the cake right away or chill it until it’s ready to serve. Once the cake sits out and the layers get softer, the cake doesn’t hold together very well. It’s super-delicious either way, but it’s definitely prettier when it’s cold and in one piece.
If you try it – let us know!
Looking for more delicious rhubarb recipes? Check these out:
Easy Homemade Strawberry-Rhubarb Jam
Summer’s Best Rhubarb Custard Pie
Hi! I'm Jeanne Fratello - a writer, reporter, and food enthusiast who is on a mission to write great stories about food and where your food comes from.
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