Rhubarb season is in full swing, which means it's time to make a fluffy, soft, aromatic, sweet-tart and incredibly delicious rhubarb upside-down cake. The most pleasant thing about this recipe is that it's incredibly simple. Besides, you can use almost any fruits and berries as filling.

Rhubarb is, strangely enough, a vegetable. However, for me it's associated exclusively with desserts, pies, sweet fillings, compotes and jellies, and you can also make very delicious rhubarb jam from it. Rhubarb freezes well, so you can prepare this juicy, sweet-and-sour filling in advance.

Prep Time
Cook Time
Total Time
 
Servings: 10 servings

Ingredients for 10 portions

Ingredients for Rhubarb Upside-Down Cake

for the batter

  • 1 cup All-purpose flour (130 g)
  • 1/2 tsp Baking powder
  • 3 Eggs
  • 1/2 cup Sugar (100 g)
  • 3 1/2 tbsp Unsalted butter (50 g)
  • 1 tsp Vanilla extract

for the filling

  • 1 lb Rhubarb (500 g)
  • 1/2 cup Sugar (100 g)

additional

  • 2 tsp Unsalted butter (10 g)

How to cook

  1. Fresh rhubarb stalks being cut into uniform pieces

    Peel the tough outer skin from the rhubarb and cut in any convenient way. If you don't peel the stems, they will be tough and fibrous.

    I wanted to make a beautiful top for the cake, so I cut the rhubarb stems considering the size of the pan.

  2. Chopped rhubarb and sugar combined in a large skillet, ready to be caramelized.

    In a dry skillet, combine the rhubarb and ½ cup of sugar.

    Put the rhubarb on the stove and caramelize it for 5 minutes on low heat. Turn the stems carefully so they don't lose their shape, especially if you want the cake to have a beautiful top.

  3. Caramelized rhubarb pieces simmering in their own juices and sugar syrup in a skillet.

    During the caramelization process, the rhubarb releases a lot of juice.

    The caramelized rhubarb stems need to be removed from heat, and the juice reduced.

  4. Rhubarb juice being reduced to a thick, bubbling syrup in the skillet.

    Reduce the rhubarb juice by 2-3 times to a syrup or caramel consistency.

  5. Caramelized rhubarb pieces neatly arranged in the bottom of a square baking pan and covered with syrup.

    Grease the cake pan with butter. Place the caramelized rhubarb on the bottom and pour the syrup over it.

    I have a square pan that is 8 by 8 inches (20 by 20 cm).

  6. Eggs and sugar in a glass bowl.

    Combine the eggs, vanilla extract, and ½ cup of sugar and beat with a mixer until the mixture is pale and fluffy.

  7. Softened butter being added to the whipped egg and sugar mixture.

    Add the 3 ½ tbsp softened room temperature butter and beat again until smooth and fully incorporated.

  8. Sifted flour being folded into the cake batter in a glass bowl.

    In portions, add the 1 cup of sifted all-purpose flour and ½ tsp of baking powder, continuing to mix until just combined.

    Optional: For a nuttier flavor and texture, you can substitute part of the flour with almond flour. Use ¾ cup of all-purpose flour and ½ cup of almond flour.

  9. A bowl of smooth, golden cake batter, ready to be poured.

    We get a uniform, smooth batter like for cupcakes.

  10. The cake batter being poured over the layer of caramelized rhubarb in the baking pan.

    Pour the batter over the caramelized rhubarb and lightly smooth it out.

    Put the cake in a preheated 350°F (180°C) oven and bake until done for 30-40 minutes.

  11. The fully baked rhubarb upside-down cake, golden brown and puffed, just out of the oven.

    Bake the upside-down cake until done. You can check doneness with a wooden skewer. It should come out of the cake completely dry.

  12. The finished rhubarb upside-down cake showing the glossy fruit topping

    While still hot, cover the cake with a suitable plate and flip it upside down with one sharp movement. Remove the pan and decorate the cake to taste.

    If you let the cake cool in the pan, it will be much harder to remove from it.

  13. The rhubarb upside-down cake, sliced and ready to be served, decorated with fresh mint

    The rhubarb upside-down cake is ready. The upside-down cake can be dusted with powdered sugar, decorated with mint leaves or served with a scoop of vanilla ice cream.

Recipe Tips

Can I use frozen rhubarb for this recipe?

Yes, absolutely! Frozen rhubarb works wonderfully here. There's no need to thaw it first. Simply add the frozen, chopped rhubarb to the skillet with the sugar. Keep in mind that it might release a bit more liquid, so you may need to cook it a minute or two longer to reduce the resulting syrup to the right consistency.

Do I really have to peel the rhubarb?

I highly recommend it, especially if your rhubarb stalks are thick and mature. The outer layer can be quite tough and fibrous, and peeling it ensures the final topping is tender and melts in your mouth. For very young, thin stalks, you might get away without peeling, but for the best texture, taking a moment to peel is worth it.

Can I use a different size or shape of pan?

Of course! I used an 8x8 inch square pan, but a 9-inch round cake pan is a perfect substitute and will give you a classic round cake. The baking time should remain roughly the same, but always check for doneness with a wooden skewer. If you use a larger pan (like a 9x13 inch), you will likely need to double the recipe for both the topping and the batter.

Why is it important to flip the cake while it's still hot

This is a crucial step! The caramelized sugar and rhubarb topping will begin to set and firm up as it cools. If you let the cake cool completely in the pan, the caramel can act like glue, making it very difficult to remove the cake without it sticking. Flipping it while hot ensures the warm, gooey topping releases easily onto the plate

My cake turned out a bit soggy. What went wrong?

A soggy bottom is a common issue with upside-down cakes, but it's easy to prevent! The most likely culprit is too much liquid from the fruit. Make sure you take the time to reduce the rhubarb juice into a thick syrup (as shown in Step 4). This concentrates the flavor and prevents the batter from becoming waterlogged. Also, ensure you don't overcrowd the pan with too much fruit.

How should I store the rhubarb upside-down cake?

The cake is best enjoyed the day it's made, possibly still a little warm. If you have leftovers, cover them loosely and store at room temperature for up to 2 days. For longer storage, you can refrigerate it in an airtight container for up to 4-5 days. Note that the caramel topping may become a bit softer in the fridge. You can serve it cold or gently warm a slice in the microwave for a few seconds.

Nutrition (per 100 g)
7.5 gFats
36.8 gCarbs
4.2 gProteins
228 ccalCalories