Warm Rhubarb Cake with Butter Sauce

There’s something special about rhubarb that takes me right back to spring afternoons in my grandmother’s kitchen. I’ve always loved how its tart flavor works so well in desserts, especially in this simple cake recipe. When you add the warm butter sauce on top, it turns into something that’ll make everyone at your table ask for seconds.

I started making this cake years ago when my neighbor shared her extra rhubarb with me, and now it’s become one of those recipes I look forward to making as soon as I spot those pink stalks at the farmers’ market. It’s the kind of dessert that doesn’t need fancy decorating or special techniques – just good ingredients and a little bit of time in the oven.

The best part? You can make the cake ahead and warm up the butter sauce just before serving. Perfect for those times when you want something homemade but don’t want to spend all day in the kitchen. Trust me, once you try this combination, you’ll be looking for excuses to make it again.

What Kind of Rhubarb Should I Use?

Both fresh and frozen rhubarb work well in this cake recipe, though each needs a slightly different approach. Fresh rhubarb stalks should be bright pink to red in color and feel firm and crisp – avoid any that are limp or have brown spots. When using fresh rhubarb, trim away any leaves (they’re not edible!) and cut the stalks into small pieces about 1/2 inch in size. If you’re working with frozen rhubarb, thaw it completely first and drain off any excess liquid to prevent your cake from becoming too wet. Keep in mind that frozen rhubarb might release more moisture during baking, so you might want to toss it with a tablespoon of flour before adding it to your batter.

Options for Substitutions

Let me share some helpful substitution tips for this cake recipe:

• Rhubarb: If rhubarb isn’t in season, you can use tart apples, cranberries, or even strawberries (though this will make it sweeter). When using apples, add 1 tablespoon of lemon juice to maintain that tart flavor rhubarb provides.
• Whipping cream: For the butter sauce, you can use half-and-half instead of whipping cream, though the sauce won’t be quite as rich. Heavy cream works perfectly too.
• Milk: Feel free to use any milk you have on hand – whole, 2%, or even plant-based options like almond or oat milk will work. Just note that non-dairy alternatives might make the cake slightly less rich.
• Plain flour: All-purpose or cake flour both work well here. If using self-rising flour, skip the baking powder and salt in the recipe.
• Butter: For the melted butter in the cake, you can use vegetable oil as a substitute. However, for the butter sauce, real butter is necessary for the right texture and flavor – this isn’t an ingredient you’ll want to swap out.

Watch Out for These Mistakes While Baking

The biggest challenge when baking with rhubarb is managing its moisture content – if you’re using frozen rhubarb, make sure to thaw and drain it completely, then pat it dry with paper towels to prevent your cake from becoming too wet. A common mistake is cutting rhubarb pieces too large, which can lead to an uneven bake and pockets of sourness – aim for pieces about 1/2 inch in size for the best texture and flavor distribution. When making the butter sauce, avoid rushing the process by cooking on high heat, as this can cause the sauce to separate or become grainy; instead, melt the butter slowly over medium-low heat and whisk constantly while adding the cream. For the perfect cake texture, don’t overmix the batter once you’ve combined the wet and dry ingredients – stop as soon as everything is just incorporated, as excessive mixing can lead to a tough, dense cake.

What to Serve With Rhubarb Cake?

This sweet and tangy rhubarb cake is already topped with a rich butter sauce, but there are still some great ways to make it even more special! A scoop of vanilla ice cream is my go-to choice – it melts perfectly into the warm cake and butter sauce, creating an amazing combination of temperatures and textures. If you’re serving this for afternoon tea, a dollop of freshly whipped cream and a cup of hot coffee make excellent companions. For an extra special touch, try adding some fresh berries on the side – strawberries are particularly nice since they’re rhubarb’s classic partner in desserts.

Storage Instructions

Keep Fresh: This rhubarb cake stays moist and yummy when kept in an airtight container at room temperature for up to 2 days. If you add the butter sauce, pop it in the fridge where it’ll stay good for up to 5 days. Just keep the sauce separate from the cake until serving time to prevent sogginess!

Freeze: Good news – this cake freezes really well! Wrap it tightly in plastic wrap, then aluminum foil, and it’ll keep in the freezer for up to 3 months. I recommend freezing the cake without the butter sauce and making the sauce fresh when you’re ready to serve.

Make Ahead: Want to prep this cake in advance? You can make the cake a day ahead and store it at room temperature. The butter sauce can be made up to 3 days ahead – just keep it in the fridge and warm it up gently when you’re ready to serve. Give it a good stir to bring it back to its smooth, creamy consistency.

Preparation Time	15-20 minutes
Cooking Time	45-60 minutes
Total Time	60-80 minutes
Level of Difficulty	Medium

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 3500-4000
• Protein: 50-60 g
• Fat: 200-220 g
• Carbohydrates: 500-550 g

Ingredients

For the cake:

• 2 cups granulated sugar
• 6 tbsp unsalted butter (melted and cooled slightly)
• 2 cups milk (whole milk for a richer cake)
• 4 tsp baking powder
• 1/2 tsp salt
• 4 cups all-purpose flour
• 4 cups rhubarb (cut into 1/2-inch pieces)

For the sauce:

• 1/2 cup unsalted butter
• 3/4 cup whipping cream
• 1 cup granulated sugar

Step 1: Prepare the Oven and Mix the Dry Ingredients

Preheat your oven to 350°F (175°C).

In a large bowl, whisk together the flour, sugar, baking powder, and salt until well combined.

This ensures that all dry ingredients are evenly distributed, which helps the cake rise evenly.

Step 2: Incorporate the Wet Ingredients and Rhubarb

Once the dry ingredients are well mixed, add in the diced rhubarb, milk, and melted butter.

Stir just until everything is combined.

Be careful not to overmix, as this can make the cake dense.

Step 3: Pour and Bake the Cake

Pour the prepared batter into a greased 9 x 13 inch baking pan, spreading it evenly with a spatula.

Place the pan in the preheated oven and bake for about 45 minutes, or until a toothpick inserted into the center of the cake comes out clean.

Once baked, remove the cake from the oven and allow it to cool.

Step 4: Prepare the Butter Sauce

While the cake is cooling, make the butter sauce.

In a heavy saucepan, combine the butter, sugar, and cream.

Bring this mixture to a boil over medium heat, stirring frequently to prevent burning.

Allow it to boil for 1 minute.

After boiling, remove the sauce from the heat and let it cool slightly.

Step 5: Serve the Cake with Warm Butter Sauce

To serve, cut the cake into pieces and generously drizzle each piece with the warm butter sauce.

The sauce can be gently reheated on the stove or in the microwave if it has cooled too much.

Enjoy your delicious rhubarb cake with its rich butter sauce topping!