Best Tasting Rhubarb Upside-Down Cake Recipe
If you are not a fan of rhubarb, but in the spring season, when you see it at the grocery store, you wonder what to make with it. This Rhubarb Upside Down cake is IT. Rye flour in the crumb, plum butter stirred into the caramel, coconut sugar in the batter. It’s the kind of bake that looks like a project and comes together in under two hours.
Quick Look at this Recipe:
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How is this recipe different?
- I added rye flour
- I added plum butter
- I used coconut sugar
Key Ingredients, Variations and Substitutions
Rhubarb – as it bakes into the brown butter caramel, it softens, releases its juices, and turns jammy and slightly glossy. Look for firm rhubarb stalks with deep red or pink coloring. Greener stalks will still taste good, but pink rhubarb gives you a more vibrant, glossy topping. Cut into even pieces so everything cooks at the same rate. If fresh rhubarb isn’t available, frozen works, but thaw it first and pat it dry so the topping doesn’t get too watery.
Rye Flour – adds a subtle earthiness and a slightly denser, but tender crumb. You don’t need a lot, just 1/4 cup mixed with all-purpose flour. If rye flour isn’t something you keep on hand, you can substitute it with whole wheat flour for a similar effect, or just use all-purpose flour if needed. The cake will be lighter and a little more neutral in flavor.
Plum Butter – this is the unexpected move in the topping. It deepens the caramel and adds a jammy stone fruit sweetness. My homemade smoked plum butter works beautifully here. You can also use a good store-bought plum jam or swap in apricot preserves.
Coconut Sugar – used in the cake batter instead of white sugar. It brings a subtle caramel warmth and keeps the crumb from tasting flat. Light brown sugar is a 1:1 swap if that’s what you have.
Other ingredients: sour cream, brown sugar, unsalted butter, orange zest (you can also use lemon zest if that is what you have), fresh ginger, allspice, cardamom, vanilla extract, eggs, all-purpose flour, baking powder, baking soda, honey, and orange juice (or lemon juice will work as well).
Equipment you will need
- 9-inch round cake pan or springform pan
- Medium saucepan
- Large mixing bowl
- Hand mixer or stand mixer
- Microplane
- Rubber spatula
- Cooling rack
Top Tips
Use room-temperature eggs, butter, and sour cream. The batter comes together much more smoothly.
Melt the butter, brown sugar, and plum butter together until the sugar begins to dissolve. This creates a more even caramel layer.
Don’t overmix the batter after adding the flour. Mix just until no dry streaks remain.
Let the cake cool for 10 to 15 minutes before inverting. Too soon, and the topping may slide. Too late, and the caramel can stick to the pan.
Step-by-step instructions
- Preheat the oven to 350°F. Butter a 9-inch round cake pan and line the bottom with parchment paper.
- In a small saucepan, melt 3 tablespoons of butter with 1/3 cup light brown sugar, 1 tablespoon plum butter, 1 teaspoon orange zest, 1 teaspoon freshly grated ginger, and 1/4 teaspoon salt over medium-low heat, stirring until smooth.
- Pour the caramel into the prepared pan, tilting it to coat the bottom of the pan evenly before adding the rhubarb.
- Build the rhubarb base. Arrange the rhubarb pieces in a single layer, evenly over the caramel.
- In a separate bowl, whisk together 1 1/2 cups all-purpose flour, 1/4 cup rye flour, 1 1/2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt, 1/4 teaspoon allspice, and 1/8 teaspoon cardamom.
- In a large bowl, using electric mixer on medium-high speed, beat 1/2 cup softened butter and 3/4 cup coconut sugar until light and fluffy, about 3 minutes.
- Add 2 eggs, one at a time, beating well after each addition.
- Mix in 1 teaspoon of vanilla extract and 1 tablespoon of orange zest. Add the sour cream.
- Add half of the flour mixture, and mix gently. Add the remaining flour mixture and mix just until combined. If the batter seems very thick, add 1 to 2 tablespoons of milk.
- Spoon the batter over the rhubarb and gently smooth the top.
- Place the pan in the preheated oven. Bake for 40 to 50 minutes at 350°F. The cake is done when the top of the cake is deep golden and springs back when lightly pressed.
- Cool in the pan for 10 to 15 minutes.
- Meanwhile, combine 1/2 cup chopped rhubarb, 1 tablespoon water, 1 tablespoon honey, 1 teaspoon orange juice, and a pinch of salt in a small saucepan. Cook until the rhubarb breaks down, about 8 minutes. For a smoother glaze, blend or strain.
- Invert the cake onto a serving wire rack. Optionally brush it with the warm rhubarb glaze.
- Serve warm or at room temperature.
Best way to enjoy
Serve slightly warm with a dollop of whipped cream.
Pair it with vanilla ice cream for dessert.
Serve it for brunch alongside fresh berries and yogurt.
If you’re looking for more baking ideas beyond this one, I have a full collection of dessert recipes worth browsing whenever the oven is on.
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Storage instructions, reheating
- Store leftovers covered at room temperature for up to 1 day.
- Refrigerate in an airtight container for up to 4 days.
- Bring slices to room temperature or warm gently in the microwave for 15 to 20 seconds before serving.
- Freeze individual slices for up to 2 months. Thaw overnight in the refrigerator.
Best Tasting Rhubarb Upside-Down Cake Recipe
Equipment
- 9-inch round cake pan or cast iron skillet
- medium saucepan
- mixing bowl
- Hand mixer or stand mixer
- Microplane
- Rubber spatula
- cooling rack
Ingredients
Rhubarb topping
- 12 oz rhubarb (cut into 1/2-inch pieces)
- 1/3 cup light brown sugar
- 3 tablespoons unsalted butter
- 1 tablespoon plum butter
- 1/4 teaspoon fine salt
- 1 teaspoon finely grated orange zest
- 1 teaspoon finely grated fresh ginger
Cake
- 1 1/2 cups all-purpose flour
- 1/4 cup rye flour
- 1 1/2 teaspoons baking powder
- 1/2 teaspoon baking soda
- 1/2 teaspoon salt (fine)
- 1/2 cup unsalted butter (softened)
- 3/4 cup coconut sugar
- 2 large eggs (room temperature)
- 1/4 teaspoon ground allspice
- 1/8 teaspoon ground cardamom
- 1 teaspoon vanilla extract
- 1 tablespoon orange zest
- 3/4 cup sour cream (room temperature)
- 2 tablespoons whole milk ()if needed for loosening batter)
Rhubarb glaze
- 1/2 cup rhubarb (chopped)
- 1 tablespoon water
- 1 tablespoon honey
- 1 teaspoon orange juice
Instructions
- Preheat the oven to 350°F. Butter a 9-inch round cake pan and line the bottom with parchment paper.
- In a small saucepan, melt 3 tablespoons unsalted butter with 1/3 cup light brown sugar, 1 tablespoon plum butter, 1 teaspoon finely grated orange zest 1 teaspoon finely grated fresh ginger, and 1/4 teaspoon fine salt over medium-low heat, stirring until smooth.
- Pour the caramel into the prepared pan, tilting it to coat the bottom evenly before adding the rhubarb.
- Wash and trim 12 oz rhubarb. Discard the leaves (they are not edible) and trim away any dry or damaged ends. Cut the stalks into ½-inch pieces. Arrange the rhubarb pieces in a single, even layer over the caramel.
- In a separate bowl, whisk together 1 1/2 cups all-purpose flour, 1/4 cup rye flour, 1 1/2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt, 1/4 teaspoon ground allspice, and 1/8 teaspoon ground cardamom.
- In a large bowl, using an electric mixer on medium-high speed, beat 1/2 cup unsalted butter and 3/4 cup coconut sugar until light and fluffy, about 3 minutes.
- Add 2 large eggs, one at a time, beating well after each addition.
- Mix in 1 teaspoon vanilla extract and 1 tablespoon orange zest. Add the 3/4 cup sour cream
- Add half of the flour mixture and mix. Add the remaining flour mixture and mix just until combined. If the batter seems very thick, add 2 tablespoons whole milk
- Spoon the batter over the rhubarb and gently smooth the surface.
- Place the pan in the preheated oven. Bake at 350°F for 40 to 50 minutes. The cake is done when the top is deep golden and springs back when lightly pressed.
- Cool in the pan for 10 to 15 minutes.
- Meanwhile, combine 1/2 cup rhubarb, 1 tablespoon water, 1 tablespoon honey, 1 teaspoon orange juice, and a pinch of salt in a small saucepan. Cook until the rhubarb breaks down, about 8 minutes. For a smoother glaze, blend or strain the mixture.
- Invert the cake onto a serving wire rack. Optionally brush it with the warm rhubarb glaze.
- Serve warm or at room temperature.
Notes
Nutrition
Did you make this recipe?
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Conclusion
Sweet-tart rhubarb, buttery brown sugar caramel, and a tender rye flour cake come together in this Rhubarb Upside Down Cake that’s anything but ordinary. Plum butter is the surprise ingredient, while orange zest, fresh ginger, allspice, and cardamom bring warmth.
Sweet and tart, my favorite kind of dessert.
FAQ
Can I use frozen rhubarb?
Yes. Thaw it completely and pat it dry before using. Frozen rhubarb releases more moisture than fresh, so skipping the pat-dry step can make the topping watery and affect the flip.
What if I don’t have rye flour?
Whole wheat flour is the closest swap and gives a similar nutty, slightly denser crumb. All-purpose flour also works fine; the cake will just be a bit lighter and more neutral in flavor.
Why did my rhubarb sink into the cake?
This usually happens when the batter is too thin or when it is poured too forcefully over the topping. Make sure your batter is thick enough to sit on top of the fruit rather than flow around it, and spoon it on gently.
Can I skip the plum butter?
You can. Replace it with apricot jam, extra brown sugar, or leave it out entirely. The topping will be a little less complex but still very good.
Can I make this in a different-sized pan?
A 9-inch round is the right fit for this recipe. An 8-inch pan will give you a taller cake with a slightly longer bake time. A 10-inch pan may spread the caramel too thin, and the cake will bake faster, so check it earlier.
