Rhubarb Cake with Butter Sauce

Rhubarb Cake with Butter Sauce is a moist, tender cake filled with tart bites of rhubarb and drenched in a warm, sweet buttery sauce that soaks into every crumb. I love the balance of tangy and sweet in this dessert—it’s cozy, rich, and just the kind of old-fashioned cake I enjoy making when rhubarb is in season. The butter sauce takes it to another level, turning every bite into a melt-in-your-mouth moment.

Why You’ll Love This Recipe

I love how simple yet nostalgic this cake feels. The rhubarb gives it a bright, tangy pop that cuts through the sweetness, and the butter sauce poured over the warm cake creates the most irresistible texture. It’s easy to make with pantry staples and works beautifully as a dessert, snack, or even breakfast. Whether I serve it warm from the oven or chilled the next day, it’s always a hit.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

For the rhubarb cake:

• all-purpose flour

• baking soda

• salt

• granulated sugar

• egg

• buttermilk

• vanilla extract

• chopped fresh rhubarb

For the butter sauce:

• unsalted butter

• granulated sugar

• heavy cream or evaporated milk

• vanilla extract

Directions

1. I preheat the oven to 350°F (175°C) and grease a 9×13-inch baking dish.

2. In a mixing bowl, I whisk together the flour, baking soda, salt, and sugar.

3. In another bowl, I beat the egg, then stir in the buttermilk and vanilla.

4. I add the wet ingredients to the dry ingredients and mix just until combined.

5. I fold in the chopped rhubarb and spread the batter evenly into the prepared dish.

6. I bake the cake for 35–40 minutes, or until golden on top and a toothpick inserted in the center comes out clean.

7. While the cake bakes, I make the butter sauce by combining butter, sugar, and cream in a small saucepan over medium heat. I bring it to a gentle boil and stir until smooth and slightly thickened. I remove it from the heat and stir in the vanilla.

8. I serve the cake warm with the hot butter sauce poured over the top or drizzled onto each individual slice.

Servings and timing

This recipe makes about 12–15 servings. It takes around 15 minutes to prep, 35–40 minutes to bake, and about 10 minutes to make the sauce. I usually plan for about an hour total from start to finish.

Variations

Sometimes I add a pinch of cinnamon or nutmeg to the batter for a warm spice note. I’ve also folded in chopped strawberries along with the rhubarb for a fruitier version. When I want a little crunch, I top the batter with a sprinkling of coarse sugar or chopped nuts before baking.

storage/reheating

I store the cake covered at room temperature for 1–2 days, or refrigerate it for up to 4 days. To reheat, I warm slices in the microwave for 15–20 seconds and reheat the butter sauce separately to pour on top. The sauce can also be stored in the fridge and gently reheated on the stovetop or in the microwave.

FAQs

Can I use frozen rhubarb?

Yes, I’ve used frozen rhubarb—just make sure to thaw and drain it well before adding it to the batter.

Do I have to use buttermilk?

Buttermilk adds a nice tang and keeps the cake tender, but I’ve used milk with a tablespoon of vinegar or lemon juice as a substitute.

Is the butter sauce necessary?

The cake is delicious on its own, but the butter sauce makes it extra indulgent. I definitely recommend it—it soaks in and makes the texture amazing.

Can I make this in advance?

Yes, I often bake the cake a day ahead. I keep the butter sauce separate and reheat it just before serving.

Can I freeze this cake?

Absolutely. I freeze it without the sauce, then thaw and warm it up when ready to serve. I make the sauce fresh or freeze it separately.

Conclusion

Rhubarb Cake with Butter Sauce is one of those timeless recipes I always come back to when rhubarb season rolls around. The tart-sweet flavor, soft crumb, and rich buttery drizzle make every bite feel like comfort food at its best. Whether I’m sharing it with guests or sneaking a warm slice for myself, this cake never fails to satisfy.