If you’re looking for ways to use up all that garden-fresh rhubarb (and want to make something different besides rhubarb crumble or rhubarb muffins) you’ve come to the right place!

This vintage rhubarb cake recipe comes courtesy of my Auntie Lee who had the recipe saved on a dog-eared recipe card. The first time I tasted it (warmed to perfection and served with a scoop of vanilla ice cream), I was hooked!

The great thing about this easy recipe is that it uses simple, wholesome ingredients you’ll likely already have in your pantry. I’m talking basics like flour, baking soda, butter, sugar, vanilla extract, buttermilk, cinnamon, and rhubarb, of course. (If you don’t have buttermilk, I’ll show you how you can make an easy substitute!)

It’s finished with a sweet topping of butter, cinnamon, and brown sugar to balance out the tartness of the rhubarb.

Plus, this is a great way to use up your rhubarb stash! Once you’ve served it to your family and friends, we’re sure you’ll be getting requests to make this tasty dessert on the regular.

Quick safety note on using rhubarb

If you’re new to using the rhubarb plant, you’ll want to check out our article all about harvesting rhubarb. To err on the side of caution, I should mention some rhubarb safety. 

Before you roll your eyes at me (I’ve met a few people who did not know this), so it’s worth repeating: the leaves of the rhubarb plant are toxic and are NOT safe to consume.

The large green leaves contain oxalic acid and will make you ill. The part of the plant we consume is the stalk (or leafstalk, if you will).

Preparing the rhubarb

Once you’ve harvested several rhubarb stalks (and removed all the leaves), simply wash and pat dry.

Dice the leafstalks into small bite-sized pieces. If your stalks are extra wide, it helps to slice them lengthwise first. That’s it! This recipe calls for raw rhubarb, so there’s no need to cook beforehand.

Tip: If using frozen rhubarb, defrost in the fridge overnight. Be sure to drain the thawed rhubarb in a strainer before using in this recipe.

Rhubarb cake ingredients

Let’s have a quick look at this cake’s ingredients.

• Butter (or margarine): This is the magic that adds richness and moisture to your cake. Butter gives a lovely creamy flavor and helps create a tender crumb. Margarine can be a handy substitute if you want something a bit lighter.
• Granulated sugar: Sugar isn’t just for sweetness—it also helps tenderize the cake by slowing down gluten formation. Plus, it aids in browning, giving your cake that inviting golden crust. Note: If you’re looking to cut back on the amount of sugar, you can substitute up to half the amount of white sugar with baking stevia.
• Egg: Eggs are the glue that hold everything together. They provide structure, help the cake rise, and add moisture. They also contribute to that beautiful golden color.
• Vanilla extract: A splash of vanilla adds warmth and depth to the flavor, enhancing all the other ingredients without overpowering the star of the show—the rhubarb.
• Flour (unbleached, all-purpose): Flour is the foundation of your cake, providing structure. It interacts with the wet ingredients to form gluten, which gives the cake its texture. Using the right amount keeps the cake tender, not tough.
• Baking soda: This is your leavening agent. Baking soda reacts with the acidity in the rhubarb and buttermilk to create bubbles, helping the cake rise and become light and fluffy.
• Diced rhubarb: The star ingredient! Rhubarb adds a tart, tangy punch that balances the sweetness. Its moisture also keeps the cake juicy and adds a lovely texture with little bursts of flavor. While nothing beats the taste of fresh rhubarb, frozen rhubarb will also work!
• Buttermilk: Buttermilk brings tanginess and moisture, complementing the rhubarb’s tartness. Its acidity also reacts with the baking soda to give your cake a perfect rise and tender crumb.

Buttermilk substitute

If you don’t have buttermilk, you can make your own by using 1 tablespoon of vinegar or lemon juice combined with 1 cup of milk. OR, you can use ½ cup sour cream with ½ cup milk. The acidic component adds a nice, tangy flavor profile to the finished cake, plus it interacts with the baking soda to help create a light, fluffy texture.

Streusel topping ingredients

While the topping is optional, I highly recommend including it as the streusel adds a sweet, golden texture to complement the tartness of the rhubarb.

• Brown sugar: Brown sugar adds a deep, caramel-like sweetness and helps create that irresistible, slightly crunchy topping.
• Cinnamon: Cinnamon brings warmth and a cozy spice that pairs beautifully with the tart rhubarb and sweet sugar, making every bite extra comforting.
• Butter: Butter binds the topping ingredients together and melts during baking to create a buttery, crumbly texture that contrasts perfectly with the soft cake beneath.

Supplies you’ll need

• 8 X 8 baking pan, or baking dish (I used a Pyrex glass dish)
• Measuring spoons and cups
• Large mixing bowl
• Small bowl (for topping)
• Mixer

Easy rhubarb cake recipe

Let’s bake a cake! If you’re expecting company, you can make this delicious cake ahead of time, and warm just before serving. This simple recipe comes together in about 15 minutes with roughly half an hour (or so) baking time.

This rhubarb cake perfectly captures the taste of rhubarb season, and you can enjoy it all year round.

Yield: One 8 X 8 baking pan

Serves: Approximately 6-8 people

Cake Ingredients:

• ½ cup butter or margarine
• 1 ½ cup white sugar
• 1 egg
• 1 teaspoon vanilla extract
• 2 cups all-purpose flour
• 1 teaspoon baking soda
• 2 cups chopped rhubarb
• 1 cup buttermilk

Topping:

• ½ cup brown sugar
• 2 teaspoons cinnamon
• 1 to 2 tablespoons of butter (or enough to create a crumbly texture)

Directions:

1. Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius). Grease baking pan.
2. Cream sugar together with the butter. Add the egg and vanilla extract.
3. Add flour and baking soda into the mixture. Slowly add buttermilk.
4. Fold in rhubarb until just incorporated.
5. Pour batter into a greased baking pan.
6. Create the topping by melting butter, and combining brown sugar and cinnamon in a small bowl. The final texture should be crumbly. Sprinkle liberally on top of the cake batter.
7. Bake in oven for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean.

Enjoy! This cake is delicious when served warm with a scoop of vanilla ice cream, or whipped cream on top!  For something a little extra, serve with sliced strawberries.

How do you store rhubarb cake?

This cake stays fresh and tasty for about 3 to 4 days when kept at room temperature, or you can pop it in the fridge to enjoy for up to a week. Just wrap the cooled cake snugly in plastic wrap or aluminum foil to keep all that deliciousness locked in. 

Related questions

Can you substitute regular milk for buttermilk?

No, I wouldn’t recommend it for this recipe. The acid in buttermilk (whether store-bought or homemade) is a crucial component of the recipe. It adds depth and a delightful tanginess, plus it works with the baking soda to leaven the batter and create a fluffy, moist texture. That’s baking magic in action! 

Can you freeze rhubarb cake?

Yes, you can freeze the cake for 3 to 4 months. When you’re ready to dig in, simply thaw it overnight in the fridge or let it sit out for a few hours at room temp—and voilà, it’s ready to enjoy all over again.

Can you put raw rhubarb in a cake?

Yes, this recipe calls for raw rhubarb that has been cleaned and diced—no need for cooking beforehand. The fresh rhubarb will bake in the oven along with the rest of the cake ingredients.

👉 If you like this post, see our Rustic Kitchen section. 🍽️