Sour Cream Rhubarb Coffee Cake
This sour cream rhubarb coffee cake is what I make the moment the first pink stalks appear at the market. It’s a simple, honest cake with a soft crumb, a jammy ribbon of rhubarb, and a brown sugar topping that stays properly crisp on top.
The batter comes together in one bowl without any fussy steps, and the rhubarb handles all the fruit filling work. You can have it in the oven in under 20 minutes, then let the kitchen fill with the smell of butter and warm spice while it bakes.
Why This Cake Works Every Time
Sour cream keeps the cake tender and just dense enough to hold up to juicy rhubarb without turning gummy. The rhubarb bakes down into soft pockets that cut through the sweetness, so each bite has a sharp little kick.
It’s the kind of bake that tastes even better the next day. That means you can make it ahead for brunch and actually relax when people arrive.
Ingredients
- 2 cups diced rhubarb: about 4 medium stalks, no need to peel, just trim the ends
- 2 tbsp granulated sugar: for tossing with the rhubarb
- 1 tbsp all-purpose flour: helps the rhubarb stay put in the batter
- 1/2 cup unsalted butter, softened: let it sit out for 30 minutes
- 1 cup granulated sugar: for the cake base
- 2 large eggs: at room temperature if you remember, but cold works too
- 1 tsp vanilla extract: the real stuff makes a difference here
- 1 cup full-fat sour cream: the fat is what keeps the crumb moist
- 2 cups all-purpose flour: spooned and leveled, not scooped
- 1 tsp baking powder
- 1/2 tsp baking soda
- 1/2 tsp fine salt
- 1/3 cup all-purpose flour: for the crumb topping
- 1/3 cup packed brown sugar: light or dark, whichever you have
- 1/2 tsp ground cinnamon
- 1/4 cup cold unsalted butter, cut into small cubes: straight from the fridge
Variations and Swaps
- Use strawberries: swap half the rhubarb for sliced strawberries. The cake will be sweeter and the filling a bit softer.
- Add orange zest: stir 1 tsp finely grated zest into the wet ingredients for a bright citrus note.
- Make it nutty: add 3 tbsp chopped pecans or walnuts to the crumb topping.
- Finish with a glaze: whisk 1/2 cup powdered sugar with 1 tbsp milk and drizzle over the cooled cake.
If you like this, try my Lemon Blueberry Buttermilk Cake for another bright, tangy bake.
How to Make Sour Cream Rhubarb Coffee Cake
Step 1: Rub the Butter into the Crumb
In a small bowl, stir together the 1/3 cup flour, brown sugar, and cinnamon. Drop in the cold butter cubes and use your fingertips to rub them into the dry mix until it looks like clumpy wet sand. Pop the bowl in the fridge while you work on the rest. The cold butter and the chill time are what give the topping those crisp, craggy bits later.
The mixture should hold together when you squeeze it, then break apart easily. If it feels powdery, keep working it for another 30 seconds.
Step 2: Toss the Rhubarb with Sugar and Flour
In a medium bowl, combine the diced rhubarb, 2 tbsp sugar, and 1 tbsp flour. Toss until every piece looks lightly coated. Set the bowl aside while you make the batter. The flour will soak up any juices the rhubarb releases and stop it from sinking straight to the bottom.
The coated rhubarb should look like frosty pink pebbles. A little extra flour in the bottom of the bowl is fine.
Step 3: Cream the Butter and Sugar
Heat the oven to 350°F (175°C) with a rack in the middle. Grease an 8-inch square baking pan and line it with a parchment sling for easy lifting. In a large bowl, beat the softened 1/2 cup butter and 1 cup sugar with a hand mixer until light and fluffy, about 3 minutes. Add the eggs one at a time, beating well after each, then mix in the vanilla and sour cream. The mixture will look a little curdled, and that’s exactly how it should look at this stage.
Scrape down the bowl once, then don’t worry about it again. A few streaks are fine.
Step 4: Alternate the Flour and Sour Cream
Whisk the 2 cups flour, baking powder, baking soda, and salt together in a separate bowl. With the mixer on low, add the dry ingredients in three additions, alternating with the cup of sour cream. Start and end with the flour. Mix just until the last streak of flour disappears; overbeating here makes the cake tough.
The batter will be thick and slightly glossy, more like a soft dough than a pourable cake batter. That thickness is what holds the rhubarb up in the oven.
Step 5: Bake the Coffee Cake
Spoon half the batter into the prepared pan and smooth it to the corners. Scatter the rhubarb evenly over the top, then dollop the remaining batter over the fruit and spread it gently with an offset spatula. Sprinkle the chilled crumb mixture over the surface, breaking up any big clumps with your fingers. Bake until the top is deeply golden and a toothpick pushed into the center comes out with moist crumbs but no wet batter, 50 to 55 minutes. If the top is browning too fast after 35 minutes, tent it loosely with foil.
The kitchen will smell like toasted sugar and cinnamon right about when you need to check on it.
Step 6: Slice and Serve
Let the cake cool in the pan on a rack for 30 minutes. Run a knife around the edge, use the parchment to lift it out, and cool it completely right side up on the rack. Once cooled, dust with powdered sugar if you like, then cut into 9 squares and serve. The top will still have a delicate snap, and the rhubarb layer will be soft and jammy throughout.
A serrated knife gives you the cleanest cut through the crumble top.
A Few Notes for the Best Rhubarb Cake
- If your rhubarb releases a lot of liquid after tossing, drain off the excess before you layer it into the pan. Too much juice can make the cake soggy.
- For the crunchiest topping, bake the cake on the upper third rack. The closer heat sets the butter fast and keeps the crumbs from sinking.
- The cake is fragile when warm. Let it cool completely before slicing, or the layers will want to pull apart.
- This cake stays moist for days, but the topping will soften a little. A quick 10-second zap in the microwave brings back some of the crispness.
Bake times by pan:
| Pan | Time |
|---|---|
| 8-inch square | 50–55 mins |
| 9-inch square | 45–50 mins |
| 9-inch round | 40–45 mins |
Storing Leftover Coffee Cake
- Refrigerate: Keep in an airtight container for up to 5 days. The cold actually firms the crumb up nicely.
- Reheating: A short blast in the microwave (15 to 20 seconds) wakes it right back up and softens the butter.
- Serve cold: Straight from the fridge, the rhubarb layer tastes extra tangy and the cake feels denser. I like it both ways.
What to Serve With Rhubarb Coffee Cake
A strong cup of black coffee is the obvious pick here. The bitterness cuts right through the sweet crumb and sharp rhubarb. If you’re serving this as a dessert later in the day, a scoop of plain vanilla ice cream melts into all the nooks and turns it into something a little more indulgent.
Frequently Asked Questions
Can I freeze this cake?
Yes. Wrap the cooled, uncut cake tightly in plastic wrap, then foil, and freeze for up to 2 months. Thaw overnight in the fridge and bring to room temperature before serving.
Can I make this the night before?
The baked cake tastes fantastic the next day, so go ahead and bake it a day ahead. I don’t recommend mixing the batter in advance because the leavening starts to lose its power.
What if I don’t have sour cream?
Plain full-fat yogurt works as a 1:1 substitute. The cake will be a little less rich but still plenty moist.
Can I double the recipe?
Yes, use a 9×13-inch pan and keep the same oven temperature. The bake time will stretch to roughly 55 to 60 minutes.
Sour Cream Rhubarb Coffee Cake Recipe
Ingredients
Method
- Mix the crumb topping ingredients and rub in cold butter until clumpy. Chill.
- Toss rhubarb with 2 tbsp sugar and 1 tbsp flour. Set aside.
- Beat 1/2 cup butter and 1 cup sugar until fluffy. Add eggs, vanilla, and sour cream.
- Whisk dry ingredients and alternate adding with sour cream mixture, mixing just until combined.
- Spread half the batter in a greased 8-inch pan, layer rhubarb, top with remaining batter, and cover with crumb topping. Bake at 350°F for 50 to 55 minutes.
- Cool in the pan 30 minutes, lift out, cool completely, then slice and serve.
