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Horizontal image of a square of dessert with a crumbly topping.

Big Crumb Rhubarb Coffee Cake

  • Author: Shanna Mallon
  • Total Time: 65 minutes
  • Yield: 9 squares 1x


This sweet rhubarb coffee cake has tasty layers of moist cake, tart rhubarb, and buttery, crunchy crumbs on top. It’s a vibrant alternative to the classic breakfast treat.



For the Filling:

  • 2 cups rhubarb (about 3 stems), chopped into small chunks
  • 1/4 cup granulated sugar
  • 2 teaspoons cornstarch
  • 1/2 teaspoon ground ginger

For the Crumb Topping:

  • 1/3 cup light brown sugar
  • 1/3 cup granulated sugar
  • 1 teaspoon ground cinnamon
  • 1/2 teaspoon ground ginger
  • 1/4 teaspoon salt
  • 1 3/4 cups all-purpose flour
  • 1/2 cup (1 stick) butter, melted

For the Cake:

  • 1/3 cup sour cream
  • 1 large egg
  • 1 large egg yolk
  • 2 teaspoons vanilla extract
  • 1 cup all-purpose flour
  • 1/2 cup granulated sugar
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon baking powder
  • 1/4 teaspoon salt
  • 6 tablespoons butter, softened


Preheat your oven to 325°F. Grease and line one 8-inch-square baking pan. Set it aside.

For the Filling:

  1. In a small bowl, mix together the rhubarb, sugar, cornstarch, and ginger. Set aside.

For the Crumb Topping:

  1. Whisk the sugars, spices, and salt in a large bowl until completely mixed together and uniform. Add the flour and whisk to combine.
  2. Add the melted butter and mix with your hand until a crumbly, semi-solid mixture forms. Push it all into the bottom of the bowl, and leave it pressed. Set aside.

For the Cake:

  1. Whisk together the sour cream, egg, egg yolk, and vanilla in a small bowl until completely smooth.
  2. In the bowl of a stand mixer fitted with the paddle attachment, combine the flour, sugar, baking soda, baking powder, and salt.
  3. Add the butter and a spoonful of the sour cream mixture. Mix on medium speed until the flour is a little moistened. Increase speed and beat for 30 seconds.
  4. Add the rest of the sour cream mixture in two batches, beating for 20 seconds after each addition, scraping down the sides of bowl with a spatula. Mix until a thick and creamy batter develops.

To Assemble and Bake:

  1. Scoop out about half of the batter into the prepared pan, and spread it evenly on the bottom. Scatter the rhubarb mixture over the batter. Spread the rest of the batter over the rhubarb.
  2. Using your fingers, break the dough-like mixture into larger crumbs, and sprinkle evenly over the cake. It will be a thick layer of crumb topping.
  3. Bake until the top starts to brown, and a toothpick inserted into center comes out clean with a few crumbs, about 45-50 minutes.
  4. Cool completely in the pan before serving.
  • Prep Time: 20 minutes
  • Cook Time: 45 minutes
  • Category: Cake
  • Method: Baking
  • Cuisine: Baked Goods

Keywords: rhubarb, coffee cake, crumb topping, breakfast