Made with creamy mascarpone, lemon zest and juice, and a hint of cardamom, this caramelized rhubarb cake is utter perfection. It is a naturally gorgeous cake with a ruby red hue from fresh local rhubarb!
This cake was inspired by ATK’s Rhubarb Upside-Down Cake from Cook’s Illustrated. I modified the recipe to use my favorite batter recipe for upside down cakes instead of using theirs. The result is gorgeous caramelized rhubarb and a delicate, buttery cake crumb.
If you’re curious how to create a gorgeous pattern for your rhubarb upside-down cake, I’ll give you all of my tips and tricks with step by step photos!
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Table of contents
Ingredients
Caramel & Rhubarb Layer:
- Unsalted butter
- Brown sugar (light or dark)
- Rhubarb
- Corn starch
- Granulated sugar
Cake Batter
- All-purpose flour
- Baking powder, baking soda, salt
- Cardamom (optional)
- Unsalted butter
- Granulated sugar
- 2 Large eggs
- Vanilla extract or vanilla bean paste
- Lemon, zest and juice
- Mascarpone cheese (can be substituted for sour cream, see recipe notes)
How to make rhubarb pattern for cake
Cut your rhubarb into uniform sized rhombus (diamond) shapes. It’s important to cut at a 45 degree angle to allow 8 slices to form a circle. My pieces were all about 1-inch long.
Toss the rhubarb in sugar and cornstarch (see recipe) and let the juices naturally draw out. This starts to soften the rhubarb.
After the caramel is made and spread on the bottom of the cake pan, go ahead and start building the pattern. Place 8 rhubarb in the center of the pan and continue building the pattern outward.
After building your pattern, fill in the edges with bits of rhubarb.
Using an ice cream scoop, place the batter gently over the pattern so that it remains undisturbed. Smooth the batter gently so it’s evenly distributed over the rhubarb.
Tips for the best upside-down rhubarb cake
- Only use a single layer of rhubarb. Too much will create a lot of excess moisture.
- Double wrap the bottom of your springform cake pan (if using) with aluminum foil to prevent leakage in the oven. A regular round cake pan will work too, but the juices may bubble up and over.
- When inverting the cake, put a plate right over the top of the springform pan and flip. This way the cake stays right on the plate without any mess.
Storing rhubarb: I recently learned that the best way to store your rhubarb in the fridge is to wrap it in aluminum foil. It keeps your rhubarb from wilting for up to 2 weeks!
No, I wouldn’t recommend freezing rhubarb upside down cake because of the moisture content in the rhubarb. Freezing and thawing will lead to a very mushy cake.
This cake is best served the same day it is made, serving slices warm or at room temperature. Leftovers can be kept in an airtight container for up to 2 days at room temperature or in the refrigerator for 4-5 days for maximum freshness.
Make a quick caramel and layer it on the bottom of a preferably round pan. Layer rhubarb slices that have been macerated in a sugar mixture. Top the rhubarb with a buttery cake batter. Then bake in the oven, let the cake cool in the pan for 15-20 minutes, and then invert the cake onto a plate or cake stand to finish cooling.
More of my favorite upside-down cakes
Caramel Apple Upside-Down Cake: The perfect fall cake with gooey caramel. This cake is best when made with fresh fall apples.
Pineapple Upside-Down Cake: Made with pineapples for the perfect cake with a tropical flavor. Great summer cake.
Banana Upside-Down Cake: Caramelized bananas are the perfect treat on top of cake any time of year!
Rhubarb Upside-Down Cake
Made with creamy mascarpone, lemon zest and juice, and a hint of cardamom, this caramelized rhubarb cake is utter perfection. It is a naturally gorgeous cake with a ruby red hue from fresh local rhubarb!
Ingredients
Caramel Apple Topping
- 5 tablespoons (75g) unsalted butter
- ¾ cup (150g) light or dark brown sugar
- 2 cups (10 oz) rhubarb, sliced or cut into 1-inch pieces
Cake
- 1 ½ cups (200g) all-purpose flour
- 1 teaspoon baking powder
- ¼ teaspoon baking soda
- ½ teaspoon salt
- ¼ teaspoon ground cardamom *optional
- ½ cup (1 stick/115g) unsalted butter, softened to room temperature
- ¾ cup plus 2 tablespoons (175g) granulated sugar
- 2 large eggs
- 1 teaspoon pure vanilla extract or vanilla bean paste
- 1 tablespoon lemon zest (from 1 lemon)
- 3 tablespoons lemon juice (from 1 lemon)
- ½ cup (226g) mascarpone cheese
Instructions
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Preheat oven to 350°F/180°C and grease a 9-inch round cake pan. For an easy release of the cake later on, line the bottom of the pan with parchment paper, and use a springform pan if you have one.
Note: wrap your springform pan with 2 layers of aluminum foil first to catch the juices that will leak out during the baking process.
Prepare the rhubarb & mascarpone mixtures:
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Combine the sliced rhubarb with corn starch and granulated sugar. Stir and set aside for several minutes. The rhubarb will start to soften and soak in its natural juices (called maceration).
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Mix together the mascarpone cheese with the juice of one lemon. It will slightly curdle, this is good. Set aside.
Make the caramel:
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In a small, deep, heavy-bottomed saucepan place butter and sugar. Cook over medium heat until butter is melted, sugar is dissolved, and mixture is bubbling, about 3 minutes. Don’t worry if the mixture Is a bit gritty and not smooth. It would all melt in the oven. Pour into prepared pan and spread in the pan until bottom is evenly covered with the caramel.
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Place the rhubarb slices flat in the pan in a random or desired pattern, covering most of the caramel layer. Don't add any juices from the bowl of rhubarb. Set aside.
Make the cake:
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In a medium bowl whisk together flour, baking powder, baking soda, salt, and cardamom. Set aside.
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In a mixer fitted with the paddle attachment, beat together butter and sugar on medium speed for 3-5 minutes until fluffy and pale in color. Scrape down the sides and bottom of the bowl as necessary.
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Add the eggs, one at a time, beating well after each addition. Beat in vanilla extract and lemon zest. On low speed, beat in the flour mixture in 3 additions, alternating it with the mascarpone in 2 additions, starting and ending with the flour, just until the batter comes together. Do not over mix.
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Scoop batter carefully over rhubarb (I use an ice cream scoop) and smooth the top. Bake for 60-65 minutes, or until a skewer inserted into the center of the cake comes out clean. Allow cake to cool in pan on a wire rack for 15-20 minutes, then run a knife along the edges of the pan and invert onto a plate (do not spring the springform pan). If you used parchment paper, gently remove it. Allow cake to cool completely on the plate.
Recipe Notes
Serving & Storing
Serve slices warm or at room temperature. Leftovers can be kept in the refrigerator for 4-5 days or at room temperature in an airtight container for up to 2 days.
Mascarpone Substitution:
If you don’t want to buy mascarpone cheese, you can easily substitute by using ⅔ cup of sour cream and omit the lemon juice instead.
