Why did my rhubarb upside down cake come out soggy?

The rhubarb likely held too much moisture. Macerate the slices with sugar and orange zest for 10 full minutes, then drain every drop of liquid you see. Tossing them with cornstarch after draining is non-negotiable. It thickens the remaining juices into a jammy glaze instead of steam that soaks the crumb.

Can I use frozen rhubarb for this cake?

Yes, but thaw it completely first. Frozen stalks release a lot of water, so drain them well and pat them very dry with paper towels. Start with 14 ounces frozen to end up with enough after draining. I add a pinch more cornstarch when tossing them to handle the extra moisture.

How do I flip the cake without it falling apart?

Cool it in the pan exactly 15 minutes, no more. Run a thin knife around the edge, place your serving plate face-down on top, then flip in one quick motion while holding both firmly together. If the caramel has started to set and you feel resistance, wrap a warm kitchen towel around the pan base for 30 seconds first.

How long does rhubarb upside down cake last in the fridge?

It keeps beautifully for up to 2 days when wrapped tightly. Press plastic wrap directly against the cut edges and add a layer of foil over that. The flavor actually deepens overnight. Pull it out 30 minutes before serving so the caramel layer softens and the crumb relaxes. No reheating needed.

Why is the top of my cake not dark and caramelized?

If the surface looks pale right out of the oven, don't worry. The residual heat from the pan continues darkening the caramel as it rests during those 15 minutes before flipping. If it's still light after resting, your oven might run cool. Use an oven thermometer to confirm 350°F, since even a 25-degree drop prevents proper browning.

Rhubarb Upside Down Cake: Perfect Tart & Sweet Recipe

Description

This rhubarb upside down cake solves the weepy topping issue by macerating the rhubarb to remove excess water, then tossing with cornstarch for a jammy layer. A buttery crumb topping bakes into a crunchy base after flipping, while orange zest and cardamom brighten the tangy fruit. Ready in 88 minutes.

Ingredients

Scale

12 oz (340g) rhubarb, sliced ½-inch thick

½ cup (100g) packed light brown sugar

¼ cup (57g) unsalted butter, plus more for pan

¾ cup (150g) granulated sugar

1 tablespoon orange zest

2 large eggs, room temperature

½ cup (120g) sour cream, room temperature

1½ cups (190g) all-purpose flour

1½ teaspoons baking powder

½ teaspoon baking soda

½ teaspoon salt

1 tablespoon cornstarch

½ teaspoon ground cinnamon

¼ teaspoon ground cardamom (optional)

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Instructions

1. Toss sliced rhubarb with 2 tablespoons of the granulated sugar and orange zest. Let sit for 10 minutes, then drain off liquid. Toss drained rhubarb with cornstarch.

2. In the cake pan, melt butter with brown sugar over medium heat until bubbly. Remove from heat. Arrange rhubarb in caramel in a single layer, prettiest slices face down.

3. Preheat oven to 350°F (175°C). Wrap base of springform pan in foil, set on baking sheet.

4. Whisk flour, baking powder, baking soda, salt, cinnamon, and cardamom (if using) together.

5. In a large bowl, rub remaining granulated sugar with orange zest until fragrant. Beat in the butter, then eggs one at a time, then sour cream until smooth.

6. Fold dry ingredients into wet just until no flour streaks remain. Spoon batter over rhubarb, spread gently to edges.

7. Scatter the crumb topping evenly over the batter.

8. Bake for 58-63 minutes, until deep golden and a tester inserted in center comes out clean of batter (caramel below will be liquid). Internal temp should reach 200°F (93°C).

9. Cool in pan exactly 15 minutes. Run a thin knife around edge, then invert onto a plate.

Notes

Macerate rhubarb with sugar and orange zest for 10 minutes to remove excess water.

Slice rhubarb horizontally into thin, flat pieces for even cooking.

Use an oven thermometer to ensure accurate baking temperature.

If the top looks pale after baking, don’t worry; the caramel darkens as it rests.

Store room temperature for up to 4 days or freezer for up to 1 months.

Prep Time: 25 min
Cook Time: 63 min
Category: Dessert
Method: Baking
Cuisine: American

Nutrition

Serving Size: 1 slice
Calories: 278 kcal
Sugar: 28 g
Sodium: 126 mg
Fat: 9 g
Saturated Fat: 6 g
Unsaturated Fat: 3 g
Trans Fat: 0 g
Carbohydrates: 45 g
Fiber: 1 g
Protein: 4 g
Cholesterol: 59 mg