This rhubarb coffee cake is a bright, tender spring dessert made with tangy rhubarb, a moist buttery crumb, and a sweet, crunchy streusel topping.
Rhubarb has a way of making spring baking feel special. Its sharp, tart flavor softens beautifully in the oven, especially when it is paired with a tender cake batter and a brown sugar crumb topping. This easy rhubarb coffee cake is simple enough for a casual weekend bake, yet delicious enough to serve for brunch, dessert, or an afternoon treat with tea or coffee.
If you have ever tasted fresh rhubarb straight from the garden, you know how bold and sour it can be. That intensity is exactly what makes it so good in baked goods. Once folded into a sweet cake batter, rhubarb becomes juicy, bright, and flavorful without overpowering the cake. Even rhubarb that is not perfectly crisp can work well here, because baking brings out its best qualities.
The amount of rhubarb may look generous when you mix it into the batter, but it bakes into the cake beautifully. Rhubarb loses some of its sharpness in the oven, so using plenty of it helps the flavor shine through. The result is a moist rhubarb coffee cake with a balanced sweet-tart flavor and a buttery streusel layer that adds just the right amount of crunch.
This is the kind of snacking cake that is easy to keep on the counter for a day or two. It slices into neat squares, travels well, and tastes just as good slightly warm as it does completely cooled. Serve it plain, with whipped cream, or with a scoop of vanilla ice cream for a more dessert-like finish.
Ingredient Notes
For the Crumb Topping
All-purpose flour
All-purpose flour gives the streusel structure and helps it bake into a crumbly topping. It also works well in the cake because it creates a sturdy but tender crumb that can hold the generous amount of rhubarb.
Brown sugar
Brown sugar sweetens the topping and adds a light molasses flavor. It pairs especially well with tart rhubarb and helps the streusel bake into a golden, slightly caramelized layer.
Butter
Unsalted butter is ideal because it lets you control the salt in the recipe. If you use salted butter, omit the pinch of salt from the streusel and reduce the salt in the cake to 1/4 teaspoon.
For the Cake
Rhubarb
Rhubarb is the key ingredient in this coffee cake. It adds a lively tartness that balances the sweetness of the batter and the streusel. Chop it into small, even pieces so it distributes evenly and bakes at the same rate throughout the cake.
Fresh rhubarb is best when it is available, but frozen rhubarb can also be used. Thaw it first and drain off any excess liquid before adding it to the batter.
For quick chopping, slice each stalk lengthwise once or twice, then cut across the stalk into small pieces.
Sour cream
Sour cream adds moisture, richness, and a subtle tang. It helps make the cake soft and tender. Greek yogurt or buttermilk can be used as a substitute.
Sugar
Granulated sugar sweetens the cake and helps create a soft crumb. Creaming the sugar with the butter also incorporates air, giving the cake a lighter texture.
Eggs
Eggs provide structure and help the cake rise evenly. Room temperature eggs blend more smoothly into the batter.
Baking Powder
Baking powder gives the cake lift. Make sure it is fresh, and do not substitute baking soda, as the two ingredients are not interchangeable.
Vanilla Extract
Pure vanilla extract adds warmth and rounds out the flavor of the cake, making the rhubarb taste even better.
Step by Step Instructions
- Preheat the oven to 350 degrees F. Grease and flour an 8 x 8 inch square baking pan.
- Make the streusel topping in a medium bowl by combining the flour, brown sugar, butter, and a pinch of salt. Mix with a fork or your fingers until crumbly, then refrigerate while you prepare the cake batter.
- In a medium bowl, whisk together the flour, baking powder, and salt.
- In a large bowl or stand mixer fitted with the paddle attachment, beat the butter and granulated sugar on medium speed until pale and fluffy, about 3 minutes.
- Add the eggs, sour cream, and vanilla. Beat until combined, scraping down the bowl as needed.
- Add the dry ingredients and mix on low speed just until no streaks of flour remain. The batter will be thick.
- Fold the chopped rhubarb into the batter by hand until evenly distributed.
- Spread the batter evenly in the prepared pan. Sprinkle the chilled streusel over the top. Bake for 50-60 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool before slicing.
This rhubarb coffee cake is delicious on its own, but it also pairs nicely with whipped cream or vanilla ice cream. For breakfast or brunch, serve it with hot coffee or tea.
Suggestions for Variations
- Replace half of the rhubarb with fresh or frozen strawberries or blueberries for a sweeter, juicier fruit combination.
- Swap half of the rhubarb for peeled, diced apples. Apples add sweetness and a soft texture that works well with tart rhubarb.
- Add a cinnamon sugar layer by mixing 1/4 cup granulated sugar with 1 teaspoon ground cinnamon and sprinkling it through the middle of the batter.
- For an almond version, replace 1/4 cup of the all-purpose flour with almond flour, add 1/2 teaspoon almond extract to the batter, and sprinkle sliced almonds over the streusel before baking.
Storage Instructions
Let the rhubarb coffee cake cool completely on a wire rack before storing. This helps prevent condensation, which can make the topping and cake soggy.
If you plan to eat the cake within 2 days, store it at room temperature in an airtight container or cover it tightly with plastic wrap or aluminum foil. For longer storage, refrigerate it the same way for up to 5 days.
Yes. Wrap the cooled cake tightly in plastic wrap and aluminum foil, then place it in a freezer-safe bag or container. Freeze for up to 3 months and thaw at room temperature before serving.
Yes. Substitute the all-purpose flour with a cup-for-cup gluten-free flour blend. For the best texture, use a blend that includes a binding agent such as xanthan gum.
Rhubarb is technically a vegetable, but it is commonly used like a fruit because its tart flavor pairs so well with sweet ingredients.
Coffee cake is usually a sweet, moist cake served with coffee. It often includes a streusel topping, but it does not usually contain coffee as an ingredient.
Rhubarb Coffee Cake
Ingredients
Topping
- 1/2 cup all-purpose flour
- 2/3 cup brown sugar
- 1/4 cup unsalted butter, cold or at room temperature
- Pinch of salt
Cake
- 1 1/2 cups all-purpose flour
- 2 teaspoons baking powder
- 1/2 teaspoon salt
- 1/2 cup butter, softened
- 2/3 cup granulated sugar
- 2 eggs, at room temperature
- 1/4 cup sour cream
- 2 teaspoons pure vanilla extract
- 3 cups rhubarb, chopped into 1/2 inch pieces
Instructions
- Preheat the oven to 350 degrees F. Grease and flour an 8 x 8 inch square baking pan.
Streusel Topping
- Combine the flour, brown sugar, butter, and salt in a medium bowl. Cut in the butter and mix until crumbly. Refrigerate while making the cake batter.
Cake
- Whisk together the flour, baking powder, and salt in a medium bowl.
- In a large bowl, cream the butter and sugar on medium speed for about 3 minutes.
- Add the eggs, sour cream, and vanilla. Beat until combined, scraping the bowl as needed.
- Add the flour mixture and mix on low speed just until combined.
- Fold in the rhubarb until evenly distributed.
- Spread the batter in the prepared pan, sprinkle with streusel, and bake for 50-60 minutes. Cool before cutting into squares.
Notes
Storage Tips
Store cooled cake at room temperature for up to 2 days in an airtight container or tightly wrapped. Refrigerate for up to 5 days, or freeze tightly wrapped for up to 3 months.