🍰 Rhubarb Cake with Butter Sauce – A Sweet & Tart Vintage Favorite

There’s something nostalgic about a slice of warm Rhubarb Cake with Butter Sauce—the kind of dessert that reminds you of grandma’s kitchen, springtime gardens, and family get-togethers. With its beautifully balanced flavor—tangy rhubarb baked into a rich, tender cake and drenched in a velvety, golden butter sauce—it’s an old-fashioned treat that still wows today.

Whether you’ve got a bundle of fresh rhubarb from your backyard or found some gorgeous stalks at the farmers’ market, this is the recipe to make them shine.

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Why You’ll Love This Rhubarb Cake

Here’s why this dessert might just become a new favorite in your seasonal baking lineup:

✅ Moist and Buttery

The cake is soft, dense yet tender, with just enough crumble to soak up that sauce.

✅ Sweet-Tart Flavor

Rhubarb adds a fresh, tangy bite that pairs perfectly with the sweet butter sauce.

✅ Easy to Make

No fancy techniques—just mix, bake, and pour.

✅ Family-Friendly Classic

This recipe is rooted in tradition and always earns rave reviews from guests.

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What Is Rhubarb, Exactly?

Rhubarb is a vegetable (yes, really!) known for its bright pink stalks and lip-puckering tartness. While technically a veggie, it’s almost always treated as a fruit in desserts. It pairs beautifully with sweet ingredients like strawberries, vanilla, and in this case, brown sugar and butter.

⚠️ Note: Only the stalks are edible—never eat the leaves, which are toxic.

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Ingredients You’ll Need

Let’s break this into two parts: the cake and the sauce.

For the Rhubarb Cake:

• 1½ cups brown sugar
• ½ cup vegetable oil (or melted butter)
• 1 large egg
• 1 cup buttermilk
• 1 tsp vanilla extract
• 2 cups all-purpose flour
• 1 tsp baking soda
• ½ tsp salt
• 2 cups fresh rhubarb, diced

🍓 Optional: Add ½ cup sliced strawberries or ½ tsp cinnamon for variety.

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For the Butter Sauce:

• ½ cup butter (1 stick)
• 1 cup sugar
• ½ cup heavy cream or evaporated milk
• 1 tsp vanilla extract

This sauce is poured warm over the cake just before serving—pure magic.

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How to Make Rhubarb Cake with Butter Sauce

Step 1: Prepare Your Pan & Oven

Preheat oven to 350°F (175°C). Grease and flour a 9×13-inch baking dish or line with parchment.

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Step 2: Make the Cake Batter

In a large bowl, mix together the brown sugar, oil, egg, buttermilk, and vanilla until smooth.

In another bowl, whisk the flour, baking soda, and salt.

Gradually stir the dry ingredients into the wet. Fold in the chopped rhubarb.

💡 Baking Tip: Toss rhubarb in a tablespoon of flour before adding to prevent it from sinking.

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Step 3: Bake the Cake

Pour the batter into the prepared pan and spread evenly.

Bake for 40–45 minutes, or until a toothpick inserted in the center comes out clean.

Cool slightly while you prepare the butter sauce.

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Step 4: Make the Butter Sauce

In a saucepan over medium heat, combine the butter, sugar, and cream. Stir constantly until the mixture comes to a gentle boil. Simmer for 2–3 minutes.

Remove from heat and stir in vanilla.

🧈 The sauce should be thickened but pourable—like warm caramel.

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Step 5: Serve It Up!

Cut the cake into squares and serve warm with a generous drizzle (or douse!) of butter sauce over the top. Add whipped cream or vanilla ice cream for an even more decadent dessert.

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Make Ahead and Storage

• Store the cake tightly wrapped at room temperature for up to 3 days.
• Refrigerate the butter sauce separately and reheat gently on the stove or microwave.
• Freeze cake squares (unsauced) for up to 2 months.

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Variations and Tips

• No buttermilk? Mix 1 cup milk with 1 tbsp lemon juice or vinegar. Let sit for 5 mins.
• Add a crumble topping of butter, oats, and brown sugar for extra texture.
• Swap in apples or pears if rhubarb isn’t in season—works great!
• Use white sugar in the cake if you prefer a lighter flavor and color.

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How to Serve Rhubarb Cake

This cake is best enjoyed:

• Warm from the oven, soaked in butter sauce
• With a scoop of vanilla bean ice cream
• With fresh strawberries or berries on the side
• At spring brunches, Easter, or Mother’s Day gatherings

It’s equally fantastic as a weekday treat or a holiday showstopper.

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FAQ

Can I use frozen rhubarb?

Yes! Just thaw and drain before using. Pat dry with a paper towel to prevent sogginess.

Is the butter sauce optional?

Technically yes—but it’s what elevates the cake from “good” to unforgettable. Don’t skip it!

Can I make this gluten-free?

Yes, use a 1:1 gluten-free flour blend and check your baking soda for cross-contamination.

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Final Thoughts

This Rhubarb Cake with Butter Sauce is a delightful celebration of tart-sweet contrast, old-fashioned comfort, and melt-in-your-mouth indulgence. Whether you’re serving it at a spring picnic or sneaking a forkful with your morning coffee, it’s a recipe that brings joy to every bite.

So go ahead—make a little sauce, slice up that rhubarb, and bake your way into a tradition worth keeping.

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