Old-Fashioned Rhubarb Crumb Cake

First of all—thank you. Every time you stop by to read, cook, or even just daydream about these recipes, it means the world to me. This blog is as much yours as it is mine, and today I’m beyond excited to share something truly special: an Old-Fashioned Rhubarb Crumb Cake that feels like a warm hug from a Scandinavian grandma.

There’s something nostalgic about rhubarb—the tartness, the way it melts into buttery batter, and the fact that it often pops up in recipes passed down through generations. And this cake? Oh, it’s a keeper. Moist, rich with buttermilk, and blanketed in the most irresistible brown sugar-cinnamon crumble. It’s perfect for fika (that cozy Scandinavian coffee break), brunch with friends, or simply sneaking a slice while standing over the sink (no judgment here).

Let’s bake a little happiness!

Ingredients

For the Crumb Topping:

• ½ cup packed light brown sugar

• ¼ teaspoon fine salt

• 1 teaspoon cinnamon

• 6 tablespoons unsalted butter, melted

• 1 cup + 2 tablespoons all-purpose flour

For the Cake:

• 4 tablespoons unsalted butter, room temperature (plus more for greasing the pan)

• 1 ½ cups of all-purpose flour, with a little extra reserved for dusting the pan

• 1 ½ teaspoons baking powder

• ½ teaspoon baking soda

• ½ teaspoon fine salt

• ¾ cup packed light brown sugar

• 1 large egg

• ⅔ cup buttermilk

• 1 teaspoon vanilla extract

• 1 ½ cups chopped rhubarb (fresh or frozen both work!)

How to Make Old-Fashioned Rhubarb Crumb Cake

Preheat and Prep

Preheat your oven to 350°F (175°C). Grease and flour a 9-inch square baking pan. You’re setting the stage for cake magic!

Make the Crumb Topping

In a small bowl, combine the brown sugar, salt, and cinnamon. Pour in the melted butter and stir. Add the flour and mix until it resembles clumpy, delicious cookie dough. Set aside.

Mix the Dry Ingredients

Combine the flour, baking powder, baking soda, and salt in a medium bowl, and whisk until evenly mixed. This blend gives the cake its signature tender crumb.

Cream the Butter and Sugar

In a stand mixer with a paddle attachment, cream the room-temperature butter and brown sugar on medium until fluffy (about 2-3 minutes). Add the egg and vanilla; mix until smooth.

Alternate Mixing

Keeping the mixer on low speed, alternate by adding a third of the buttermilk, then a third of the dry mixture. Repeat until everything’s in. Mix just until combined.

Fold in Rhubarb

Gently fold the chopped rhubarb into the batter with a spatula. Don’t overmix—tenderness is the goal!

Assemble and Bake

Pour the batter into the prepared pan. Crumble the topping over, squeezing it slightly in your hands to form little nuggets of joy. Bake for 40–50 minutes or until a toothpick comes out clean and the topping is beautifully golden.

Cool and Serve

Let the cake cool to room temp before slicing. (I know it’s hard to wait—trust me!)

Helpful Tips

• Room temp butter = fluffier cake
  Don’t skip this step; it really makes a difference!

• Frozen rhubarb?
  No problem! Just thaw and drain it well before using.

• Want extra texture?
  Toss a handful of chopped nuts—pecans or walnuts work great—into the crumb topping for added crunch.

Substitutions & Variations

• No buttermilk? Use ⅔ cup milk mixed with 2 teaspoons lemon juice or vinegar. Let it sit for 5 minutes before using.

• Switch the fruit: Chopped strawberries or blueberries can be used if rhubarb’s not in season.

• Make it dairy-free: Swap butter for vegan margarine and use plant-based buttermilk (almond milk + vinegar works well!).

Frequently Asked Questions

Can I make this ahead of time?

Yes! It actually tastes even better the next day. Just wrap tightly once cooled.

Can I freeze rhubarb crumb cake?

Absolutely. Slice it, wrap in plastic, and store in a freezer-safe bag. It’ll keep for up to 3 months.

How do I reheat it?

Microwave slices for about 20 seconds or warm in a 300°F oven until just heated through.

Storage Instructions

Keep the cake in an airtight container on the counter for up to 3 days, or in the fridge for as long as 5 days. To freeze, wrap slices individually and store in a zip-top freezer bag for up to 3 months.

More Cozy Bakes to Try

• Rhubarb Dream Bars Recipe

Have a question I didn’t cover? Pop it in the comments—I’m always happy to chat about cake.

And if you try this Rhubarb Crumb Cake, please let me know how it turned out! Nothing makes me happier than hearing your stories from the kitchen.

Old-Fashioned Rhubarb Crumb Cake

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• Author: Lisa
• Total Time: 1 hour to 1 hour 10 minutes
• Yield: 9 servings 1x
• Diet: Vegetarian

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Description

A nostalgic, buttery buttermilk cake loaded with tart rhubarb and crowned with a cozy cinnamon-brown sugar crumble. This Old-Fashioned Rhubarb Crumb Cake is perfect for brunch, fika, or a quiet moment with coffee. It’s tender, flavorful, and anything but boring!

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Ingredients

Scale 1x2x3x

For the Crumb Topping:

½ cup packed light brown sugar

¼ teaspoon fine salt

1 teaspoon ground cinnamon

6 tablespoons unsalted butter, melted

1 cup + 2 tablespoons all-purpose flour

For the Cake:

4 tablespoons unsalted butter, room temperature (plus extra for greasing the pan)

1 ½ cups of all-purpose flour, with a little extra reserved for dusting the pan

1 ½ teaspoons baking powder

½ teaspoon baking soda

½ teaspoon fine salt

¾ cup packed light brown sugar

1 large egg

⅔ cup buttermilk

1 teaspoon vanilla extract

1 ½ cups chopped rhubarb (fresh or frozen, thawed and drained)

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Instructions

• Preheat oven to 350°F (175°C). Grease and flour a 9-inch square baking pan.

• Make the crumb topping: In a bowl, stir together the brown sugar, salt, and cinnamon. Add melted butter and stir until combined. Mix in the flour until clumps form. Set aside.

• Mix dry ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

• Cream butter and sugar: In a stand mixer, beat the butter and brown sugar until fluffy. Add the egg and vanilla, mixing until smooth.

• Alternate mixing: On low speed, alternate adding a third of the buttermilk and a third of the dry mixture. Repeat until just combined.

• Fold in rhubarb gently with a spatula.

• Assemble the cake: Pour batter into the prepared pan. Sprinkle the crumb topping over, gently pressing to form small clusters.

• Bake for 40–50 minutes or until a toothpick inserted in the center comes out clean.

• Cool completely before slicing and serving.

Notes

Want a little crunch? Toss chopped pecans or walnuts into the crumb topping.

Frozen rhubarb works just fine—just be sure to thaw and drain it well.

To make dairy-free: swap butter for vegan margarine and use almond milk + vinegar as a buttermilk substitute.

This cake is even better the next day!

• Prep Time: 20 minutes
• Cook Time: 40-50 minutes
• Category: Breakfast
• Method: Baking
• Cuisine: Scandinavian, Norwegian-inspired

Nutrition

• Serving Size: 1 slice (1/9th of the cake)
• Calories: 378
• Sugar: 23g
• Protein: 4g
• Cholesterol: 45mg