Sweet, tangy, and totally show-stopping.
This cake is one of those “how is it this good?” recipes.
The rhubarb gets all glossy and caramel-like on the bottom (which becomes the top!), and the buttery cake underneath is soft, moist, and slightly tangy. 3
It’s great for spring and early summer when rhubarb is in season. You can make it for a brunch, dessert, or just because you’re craving something special.
🍰 Why I Love This Recipe
This cake brings back memories of my grandma’s kitchen in early summer. She grew rhubarb in her backyard, and I remember helping her cut it fresh, then watching the magic happen as it transformed in the oven.
- That sweet-tart rhubarb topping is so pretty and shiny.
- It’s a one-pan bake that looks fancy but is easy to make.
- The flavors are balanced: not too sweet, with a nice tang.
- It makes your whole kitchen smell amazing while it bakes.
Servings: 8
Total Time: About 1 hour 10 minutes (30 min prep, 40 min bake)
🛒 What You’ll Need
For the Rhubarb Topping:
- 4 tablespoons unsalted butter
- ¾ cup light brown sugar, packed
- 3 cups rhubarb, chopped into ½-inch pieces
For the Cake Batter:
- 1½ cups all-purpose flour
- 1½ teaspoons baking powder
- ¼ teaspoon salt
- ½ cup (1 stick) unsalted butter, softened
- ¾ cup granulated sugar
- 2 large eggs
- 1 teaspoon vanilla extract
- ½ cup sour cream
- ¼ cup whole milk
👩🍳 Pro Tips
- Slice the rhubarb evenly so it cooks and caramelizes at the same rate.
- Don’t overmix the batter or the cake might come out tough.
- Let the cake cool for 10 minutes before flipping—any longer and the caramel might stick.
- If your rhubarb is extra tart, sprinkle a little more sugar over it before baking.
- Sour cream adds moisture and tang—don’t skip it!
🧰 Tools You’ll Need
- 9-inch round cake pan
- Mixing bowls
- Hand mixer or stand mixer
- Rubber spatula
- Saucepan
- Cooling rack
- Measuring cups and spoons
🔄 Substitutions and Variations
- No rhubarb? Use chopped strawberries, apples, or peaches.
- Dairy-free? Use vegan butter and dairy-free yogurt or sour cream.
- Brown sugar substitute: Coconut sugar can work in a pinch.
🕒 Make Ahead Tips
- You can chop the rhubarb and mix the dry ingredients the day before.
- The cake keeps well covered at room temp for 1–2 days.
- Reheat slices in the microwave for 10–15 seconds for that fresh-from-the-oven feel.
🧪 Why This Recipe Works (Quick Science)
Rhubarb has a lot of water and a sharp tang. Caramelizing it with butter and brown sugar first helps soften it and mellow the acidity. The sour cream in the cake adds moisture and a bit of acid, which reacts with the baking powder to give you a soft, fluffy crumb.
❌ Common Mistakes
- Using cold butter in the batter: It won’t cream properly and your cake could be dense.
- Overbaking: Rhubarb can dry out. Start checking around 35 minutes.
- Skipping the cooling time before flipping: The caramel won’t set enough and may run off.
🍴 What to Serve With
- Whipped cream or crème fraîche
- A scoop of vanilla ice cream
- Fresh berries on the side
- Hot coffee or a chilled glass of rosé
🔥 Step-by-Step Instructions
Step 1: Caramelize the Rhubarb Topping
Melt 4 tbsp butter and stir in ¾ cup brown sugar in a saucepan over medium heat. Once smooth, remove from heat and pour into your greased 9-inch cake pan. Spread evenly, then scatter 3 cups of chopped rhubarb on top.
Step 2: Mix Dry Ingredients
In a bowl, whisk together 1½ cups flour, 1½ tsp baking powder, and ¼ tsp salt.
Step 3: Cream Butter and Sugar
In another bowl, beat ½ cup softened butter and ¾ cup granulated sugar until light and fluffy.
Step 4: Add Eggs and Vanilla
Beat in 2 eggs, one at a time, then mix in 1 tsp vanilla extract.
Step 5: Mix in Sour Cream and Milk
Stir in ½ cup sour cream and ¼ cup milk until smooth.
Step 6: Add Dry Ingredients
Gradually add the dry mix to the wet, mixing just until combined.
Step 7: Assemble and Bake
Pour the batter over the rhubarb topping and spread evenly. Bake at 350°F for 40 minutes or until a toothpick comes out clean.
Step 8: Cool and Flip
Let the cake cool for 10 minutes. Run a knife around the edge, place a plate on top, and carefully flip it over.
🧊 Leftovers & Storage
- Store covered at room temp for up to 2 days.
- Refrigerate for up to 5 days.
- Warm slices in the microwave before serving.
❓ FAQ
Can I use frozen rhubarb?
Yes! Thaw and drain it well so it doesn’t water down the caramel.
Can I make this gluten-free?
Yes, use a 1:1 gluten-free baking flour blend.
Why did my topping stick to the pan?
Most likely it cooled too long or your pan wasn’t greased well.
Can I double the recipe?
Yes, use a 9×13 pan and extend the baking time by 10–15 minutes.
💬 Wrap-Up
I hope you try this caramelized rhubarb upside down cake—it’s sweet, a little tart, and just the right kind of special. Let me know how yours turns out! Leave a comment with your questions, tips, or just to share how fast it disappeared from your table. 🥰
