Sour Cream Rhubarb Coffee Cake

Here’s a coffee cake that’s bright and lively thanks to fresh rhubarb, wrapped in a tender sour-cream–enriched batter. It’s just the right level of tangy, and the cinnamon–brown sugar topping with optional nuts adds a lovely crunch that makes every bite cozy and comforting. This cake stands out on your breakfast table, pairs wonderfully with afternoon tea, and makes a simple but special after-dinner treat.

The best part? It’s simple and forgiving to make. You’ll spend around 15 minutes mixing and prepping, then pop it in the oven for 45 to 50 minutes—about an hour total. No fancy tools or techniques needed. Just mix up common ingredients, fold in diced rhubarb, sprinkle that buttery topping over it, and bake. Easy!

Scroll down for the full list of ingredients and step-by-step instructions, along with my tips to help you get that perfect soft, moist crumb every time. I’ll also give you ideas to tweak the recipe if you want to switch it up—whether you need gluten-free, nut-free, or fancy a crisp streusel instead. Let’s make a crowd-pleaser that feels just like home!

What Makes This Cake Special

This coffee cake is such a great way to celebrate rhubarb when it’s in season. The magic happens with the sour cream and baking soda combo, which gives the crumb that soft, tender, and just slightly tangy texture that blends beautifully with the sharpness of the rhubarb. Then there’s the warm cinnamon and caramel-like brown sugar topping, bringing a sweet and crunchy balance that makes every bite feel cozy and irresistible. If you enjoy that cinnamon-kissed rhubarb flavor, you might also like my Cinnamon Rhubarb Bread. Plus, it’s super easy to make, making it perfect for sharing mornings with your family or bringing along to friends. For a make-ahead breakfast with the same tangy-sweet rhubarb vibe, try Rhubarb Overnight Oats.

Ingredients and Measurements

• 1 cup sour cream
• 1 teaspoon baking soda
• ½ cup unsalted butter, softened to room temp
• 1 ½ cups granulated sugar
• 1 large egg
• 1 teaspoon pure vanilla extract
• 2 cups all-purpose flour
• ½ teaspoon salt
• 2 cups fresh rhubarb, diced into about ½-inch pieces
• ½ cup packed brown sugar
• 1 teaspoon ground cinnamon
• ¼ cup chopped walnuts or pecans (optional)

Step by Step Baking Directions

1. Preheat oven to 350°F (175°C) and grease and lightly flour a 9-inch square pan or line it with parchment.
2. Whisk sour cream and baking soda in a small bowl until fizzed and thickened; set aside.
3. Beat softened unsalted butter with granulated sugar in a large bowl until pale and fluffy.

4. Add the egg and vanilla extract to the butter-sugar mixture and mix until combined.

   
5. Stir the sour cream mixture into the butter-sugar mixture until incorporated.
6. Slowly fold in all-purpose flour and salt until just combined, avoiding overmixing.
7. Gently fold in diced rhubarb until evenly distributed.

8. Pour the batter into the prepared pan and smooth the top.

   

9. In a separate bowl, combine brown sugar, ground cinnamon, and chopped nuts (optional) and sprinkle the topping evenly over the batter.
10. Bake 45–50 minutes, until a toothpick inserted into the center comes out clean or with a few moist crumbs.

11. Cool the cake in the pan before slicing.

    

Baker’s Tips for Best Results

• Use room-temperature butter and egg so they cream together smoothly, giving your cake a lighter texture.
• Let the sour cream and baking soda fizz and thicken before mixing it in—that little chemical reaction is what tenderizes the crumb.
• Cut your rhubarb into even ½-inch pieces so it bakes evenly. If using frozen, thaw fully and pat dry to avoid sogginess.
• To keep rhubarb from sinking to the bottom or releasing too much moisture, toss it with a tablespoon of flour before folding it into the batter—a trick that also works beautifully in quick breads like Irresistible Rhubarb Bread.
• Mix the flour gently and only until just combined—overmixing develops gluten and makes cakes tough.
• Grease your pan well, or line it with parchment for an easy lift-out and neat slices.
• Start checking your cake at the 45-minute mark. A toothpick should come out clean or with a few moist crumbs, but not wet batter.
• Toast nuts briefly before mixing into topping for a deeper flavor boost. Or leave out altogether for a nut-free cake.
• Add in a teaspoon of orange or lemon zest, or a pinch of nutmeg, to the batter for extra flavor layers that pair wonderfully with rhubarb; for a citrus-forward bake, see Lemon Rhubarb Loaf.
• Store cooled cake in an airtight container. Refrigerate up to 5 days or freeze for up to 3 months. Warm slices in the microwave for 20 seconds or bake at 350°F for 10 minutes before serving.

Easy Variations and Substitutions

• Swap out the rhubarb for strawberries or raspberries if you want a sweeter, fruitier version.
• Try Greek yogurt instead of sour cream for a tangier taste and a bit healthier option—it shines in bakes like these blueberry oatmeal Greek yogurt muffins.
• Use a streusel topping made from flour, sugar, butter, and oats for a crispier, more crumbly finish instead of cinnamon-nut topping—similar to the crumb on these coffee cake muffins.
• Make it gluten-free by swapping the all-purpose flour with your favorite gluten-free baking mix.
• Add a teaspoon of orange zest into the batter for some bright citrus aroma that pairs beautifully with the tang of rhubarb.

Storage and Reheating Advice

Once your coffee cake cools, store it in an airtight container at room temperature for up to two days. For keeping it fresh longer, refrigerate the cake for up to five days, or freeze it for up to three months. When you’re ready to enjoy a slice, warm it gently in the microwave for about 20 seconds or pop it in a 350°F oven for 10 minutes until warmed through. This’ll bring back that freshly-baked softness and flavor we all love. Prefer another make-ahead breakfast that reheats beautifully? Try my Blueberry Cottage Cheese Breakfast Bake.

Quick Answers to Common Questions

What can I substitute for sour cream?

Greek yogurt is a fantastic substitute, offering a similar tang and creaminess. You could also use buttermilk or crème fraîche if you have those on hand. Just keep the quantity the same to maintain that tender texture.

Can I use frozen rhubarb?

Yes, frozen rhubarb works well! Just be sure to thaw it completely and pat it dry to remove any extra moisture. For more tips on prepping frozen rhubarb for baking, see the Classic Rhubarb Crisp with Frozen Rhubarb.

How do I know when the coffee cake is done?

The best test is inserting a toothpick into the center of the cake. If it comes out clean or with just a few moist crumbs clinging, your cake is perfectly baked. Avoid waiting until the toothpick is completely dry to prevent a dry cake.

Can I make this cake ahead of time?

Definitely! You can bake this cake a day or two in advance. Once cooled, cover it tightly and store at room temperature for up to two days, or refrigerate for longer freshness. Just warm slices briefly before serving for that fresh-out-of-the-oven feel.

Is this recipe nut-free?

Absolutely, just skip the nuts in the topping. The cake stays moist and flavorful without them, making it perfect if you’re accommodating nut allergies.

Can I use brown sugar instead of granulated sugar in the batter?

Yes, you can substitute all or part of the granulated sugar with brown sugar. This swap gives the cake a richer, slightly caramel-like flavor and adds moisture. Just keep in mind it may darken the color a bit.

What type of pan should I use?

I recommend a 9-inch square baking pan for the best baking time and shape. But you can also use a similar-sized round or rectangular pan—just keep an eye on the baking time, as it may vary slightly.

Can I add spices to the batter?

Absolutely! Spices like cinnamon, nutmeg, or even a little cardamom blend really well with rhubarb. Feel free to add about ½ to 1 teaspoon of your favorite spices right into the batter.

How do I dice rhubarb properly?

Wash the rhubarb stalks, trim off the leaves and ends, then cut into uniform pieces about ½-inch in size. Uniform chunks help the rhubarb bake evenly throughout the cake without sinking.

Can I double this recipe?

Yes, doubling works great! Use a larger pan or split the batter between two pans. Just remember to watch the baking time, as larger volumes may take a bit longer to cook through.