Old-Fashioned Rhubarb Upside-Down Cake is the kind of dessert I make when I want something simple that still feels special on the table. The brown sugar rhubarb topping turns glossy and sticky, and the cake bakes up soft and tender underneath.
Rhubarb has that tart, bright flavor I really like in desserts, especially when it’s paired with a vanilla buttermilk cake. This version tastes classic to me, with a buttery caramel edge from the topping and a crumb that stays light.
I serve this warm or room temperature, and I almost always add whipped cream or vanilla ice cream. It’s especially nice in spring and early summer when rhubarb is easy to find.
Why You’ll Love This Recipe
Old-school and reliable: It has that classic upside-down cake look, with fruit on top and a simple vanilla cake underneath.
That glossy topping: Brown sugar and butter make a sticky, shiny layer that soaks just a little into the cake around the edges.
Tender cake crumb: Buttermilk keeps the cake soft and light, and it stays nice even after it cools.
Rhubarb flavor comes through: The tartness doesn’t get lost, which is exactly what I want from a rhubarb dessert.
Easy to serve: Slice it like any cake, then add whipped cream or ice cream and you’re done.
Ingredients You’ll Need
Rhubarb Topping
- Unsalted butter: Butter is doing a lot of work here, both for the caramel-style topping and for a rich flavor. I use unsalted so I can control the salt.
- Light brown sugar: Light brown sugar gives that classic caramel taste and a softer sweetness. Dark brown sugar works too if that’s what you have.
- Rhubarb: Fresh rhubarb is great, but frozen works fine here too. If you use frozen, make sure it’s thawed and really well drained so the topping doesn’t get watery.
- Lemon juice: This keeps the fruit tasting bright and helps the rhubarb taste more “rhubarb,” if that makes sense.
- Salt: Don’t skip it. A little salt keeps the topping from tasting flat and overly sweet.
Cake Batter
- All-purpose flour: I use regular flour here. No need for cake flour.
- Baking powder: Helps the cake rise and stay fluffy.
- Baking soda: Works with the buttermilk to give the cake a lighter crumb.
- Fine salt: A small amount makes the vanilla flavor pop more.
- Unsalted butter: Make sure it’s softened so it creams easily with the sugar.
- Granulated sugar: This keeps the cake sweet and clean-tasting next to the tart rhubarb.
- Eggs: Room temperature eggs mix in more smoothly, and the batter stays more even.
- Vanilla extract: Use a vanilla you like the taste of, because it’s the main flavor in the cake.
- Buttermilk: This is what makes the cake tender and a little tangy. If you don’t have it, the quick milk-and-lemon swap works well.
Optional
- Ground cinnamon: I like a little cinnamon with rhubarb, especially if you want a warmer, more old-fashioned flavor.
- Whipped cream or vanilla ice cream: I usually go with vanilla ice cream if I’m serving it warm, and whipped cream if it’s room temp.
Recipe Instructions
- Preheat the oven: Heat the oven to 350°F and set a rack in the center. Grease a 9-inch oven-safe skillet or a 9-inch cake pan.
- Melt the butter: Melt the butter for the topping in the skillet over medium heat.
- Cook the brown sugar: Stir in the brown sugar and cook until it looks glossy and bubbling, about 1 minute.
- Add the rhubarb: Stir in the rhubarb, lemon juice, and salt. Cook for 2 to 3 minutes, just until the rhubarb is coated and slightly softened.
- Spread the topping: Spread the rhubarb into an even layer, then remove the pan from the heat. If you’re using a cake pan, scrape the topping into the pan and level it out.
- Mix the dry ingredients: Whisk the flour, baking powder, baking soda, and salt in a medium bowl.
- Cream the butter and sugar: Beat the softened butter and granulated sugar until light and fluffy, about 2 to 3 minutes.
- Add the eggs and vanilla: Beat in the eggs one at a time, then mix in the vanilla until combined.
- Add the dry ingredients: Add the dry ingredients in two additions, alternating with the buttermilk. Mix just until you don’t see dry flour.
- Add the batter to the pan: Spoon the batter over the rhubarb layer and gently spread it to the edges.
- Bake: Bake for 40 to 45 minutes, until the top is golden and a toothpick inserted in the center comes out clean.
- Cool in the pan: Let the cake cool in the pan for 10 to 15 minutes.
- Invert the cake: Run a thin knife around the edge, then invert onto a serving plate.
- Cool and serve: Let the cake cool at least 15 minutes before slicing. Serve warm or room temperature with whipped cream or vanilla ice cream.
Some of my tips!
This is the part that really makes a difference. If you only read one section, make it this one because this is where I share the little trick that helps the recipe turn out so well.
Recipe Tips & Tricks
Use a pan you trust for releasing. A skillet is really forgiving for upside-down cakes, but a cake pan works too. If you use a cake pan, parchment on the bottom makes flipping a lot less stressful.
Don’t overcook the rhubarb. You just want it coated and barely softened. If it cooks too long on the stove, it can turn mushy after baking.
Keep the butter properly softened. If it’s too cold, it won’t cream well and the cake can bake up a bit heavy. If it’s melty-soft, the batter can get loose and greasy.
Stop mixing as soon as the flour disappears. Overmixing makes the crumb tougher. I usually finish with a spatula to avoid going too far.
Flip while it’s still warm. If you wait too long, the brown sugar layer can stick as it cools. That 10 to 15 minute window is about right.
Make some touches!
There are plenty of easy ways to serve this depending on the occasion. Keep it simple, or add a few small touches to make it feel a little more special.
Serving Suggestions
- Vanilla ice cream: A scoop on the side is my favorite, especially if the cake is still a little warm. The cold ice cream with the tart topping just works.
- Whipped cream: Soft whipped cream is great if you’re serving this at room temperature. I like it with a tiny pinch of salt stirred in.
- Extra fruit: A handful of sliced strawberries or raspberries on the plate is nice with rhubarb. It makes it feel a little more complete without doing much.
- Coffee or tea: This is really good with black coffee or a simple cup of tea. It’s the kind of cake I like for an afternoon slice.
Save it for later
This section covers how to store leftovers and what parts of the recipe you can prepare ahead of time.
Storage and Make Ahead
Store leftovers covered in the fridge for up to 4 days. I usually just cover the plate or move slices into a container. The topping will firm up a bit when it’s cold.
To serve, you can eat it cold, but I like it warmed. A quick microwave warm-up for individual slices works well, or warm the whole cake in a low oven until it’s heated through.
If you want to make this cake ahead, bake it the day before and keep it chilled. Let it sit at room temperature for a bit before serving, or warm slices as needed.
You can also freeze individual portions if you want them to last longer. Thaw in the fridge overnight, then warm if you like.
A few quick answers
This section covers a few extra details that may help before you head to the recipe card.
Recipe FAQs
Can I use frozen rhubarb?
Yes. Thaw it first and drain it well so you’re not adding a lot of extra liquid to the topping.
What’s the easiest buttermilk substitute for this cake?
Mix milk with a little lemon juice and let it sit for about 5 minutes, then use it like buttermilk. It’s not exactly the same, but it works well in this batter.
How do I know when the cake is done?
Look for a golden top and a toothpick that comes out clean from the center. If the top is browning fast but the center isn’t done, tent it loosely with foil for the last part of baking.
Why did my topping stick to the pan?
This usually happens if the cake cools too long before flipping, or if the pan wasn’t greased well. Next time, flip it after about 10 to 15 minutes of cooling, and consider parchment on the bottom if you’re using a cake pan.
Can I add cinnamon?
You can, and it’s really nice with the brown sugar and rhubarb. I keep it light so it doesn’t take over the vanilla cake.
You might also like
Before you go, take a look at a few other recipes below the recipe card. They use similar ingredients in a different way and are worth saving too.
MORE DINNER RECIPES TO TRY
Old-Fashioned Rhubarb Upside-Down Cake
INGREDIENTS
Rhubarb Topping
- 6 tbsp unsalted butter
- 3/4 cup light brown sugar packed
- 3 cups rhubarb chopped into 1/2 inch pieces
- 1 tbsp lemon juice
- 1/4 tsp salt.
Cake Batter
- 1 1/2 cups all purpose flour
- 1 1/2 tsp baking powder
- 1/2 tsp baking soda
- 1/2 tsp fine salt
- 1/2 cup unsalted butter softened
- 3/4 cup granulated sugar
- 2 large eggs room temperature
- 1 tsp vanilla extract
- 1/2 cup buttermilk.
Optional
- 1 tsp ground cinnamon
- whipped cream or vanilla ice cream for serving.
INSTRUCTIONS
Prepare Pan and Topping
- Heat oven to 350 F and place a rack in the center
- grease a 9 inch oven safe skillet or 9 inch cake pan
- melt 6 tbsp butter in the skillet over medium heat then stir in brown sugar and cook until glossy and bubbling about 1 minute
- stir in rhubarb lemon juice and 1/4 tsp salt then cook 2 to 3 minutes just to coat and lightly soften
- spread rhubarb into an even layer and remove from heat.
Make Batter and Bake
- Whisk flour baking powder baking soda and salt in a bowl
- beat softened butter and granulated sugar until light and fluffy 2 to 3 minutes then beat in eggs one at a time and mix in vanilla
- add dry ingredients in two additions alternating with buttermilk mixing just until combined
- spoon batter over rhubarb layer and gently spread to the edges
- bake until golden and a toothpick inserted in the center comes out clean 40 to 45 minutes.
Cool and Serve
- Cool cake in the pan 10 to 15 minutes
- run a thin knife around the edge then invert onto a serving plate
- cool at least 15 minutes before slicing and serve warm or room temperature with whipped cream or ice cream.
