Marble Crumb Cake

Marble Crumb Cake (Gluten-free)

You’re gonna want to add this moist, chocolate-ribboned coffee cake to your to-bake list, like, now. Much like its crumb cake counterparts, a square of this tasty marble cake is a welcome — and totally indulgent — way to start the day. Wash a slice down with your favorite cup of joe, hot or iced, and a smile is sure to spread across your face!

What’s your favorite way to use up a tub of sour cream (the secret to this tender cake)? Do you go savory or sweet? Let’s talk in the comments or on Facebook or Twitter!

Marble Crumb Cake (Gluten-free)

Marble Crumb Cake

(cake batter heavily adapted from Bon Appétit, March 2002)

Preparation Time: 20 minutes

Baking Time: 45 minutes

Serves: About 9


Cake Batter:

  • 46 grams (14 cup plus 2 tablespoons) millet flour
  • 46 grams (14 cup plus 2 tablespoons) garbanzo fava flour
  • 60 grams (14 cup plus 1 tablespoon) potato starch
  • 24 grams (3 tablespoons) arrowroot starch
  • 12 teaspoon xanthan gum
  • 14 teaspoon fine sea salt or table salt
  • 12 teaspoon baking soda
  • 12 teaspoon baking powder
  • 85 grams (6 tablespoons) unsalted butter, softened
  • 144 grams (34 cup) evaporated cane juice or granulated white sugar
  • 1 large egg
  • 160 grams (23 cup) sour cream
  • 2 teaspoons (10 grams) vanilla extract
  • 57 grams (2 ounces) bittersweet chocolate, melted and cooled slightly


  • 40 grams (13 cup) millet flour
  • 38 grams (13 cup) almond meal/flour
  • 48 grams (14 cup) potato starch
  • 12 teaspoon xanthan gum
  • Pinch fine sea salt or table salt
  • 14 teaspoon Baking Soda
  • 14 teaspoon Baking Powder
  • 64 grams (13 cup) golden brown sugar
  • 57 grams (4 tablespoons) unsalted butter, melted and still warm
  • 12 teaspoon vanilla extract


  • Additional butter, for greasing pan
  • Powdered sugar (optional), for serving


Prepare Cake:

Position rack in the center of the oven and preheat to 350°F. Butter a 9″ square metal baking pan and line with a sheet of parchment paper (do not trim overhang on the sides, this serves as a handle to lift cake out after it is baked — see this photo for additional clarification). Lightly grease the two exposed pan ends with butter.

Whisk together millet flour through baking powder in a small bowl. In the bowl of a stand mixer fitted with the paddle attachment, beat softened butter at medium speed (#4 on a KitchenAid) until smooth, about 1 minute. Scrape down the bowl and beater. Add sugar and beat (on medium speed) until well combined and fluffy, about 3 minutes, scraping down the bowl half way through. Add egg, beat on medium until well blended, about 1 minute. Add sour cream and vanilla extract and beat just until blended, about 15 seconds. Scrape down bowl, turn the mixer on low and add flour mixture; stir just until incorporated, about 30 seconds.

Combine 1/4 cup (2 ounces) of cake batter with the melted, bittersweet chocolate in a small bowl, stirring well; set aside. Transfer vanilla cake batter to prepared baking dish, spread into an even layer — an offset spatula is really helpful here. Dollop spoonfuls (about 1 tablespoon each) of the chocolate cake batter over top. Run a knife through all of the colors, swirling to create a marbled effect.

Make Topping:

In a medium bowl, whisk together millet flour through brown sugar; set aside. Combine still-warm melted butter and vanilla extract. Stir butter mixture into flour mixture until well blended. Squeeze small handfuls of topping together to form clumps, sprinkle evenly — breaking clumps up as necessary — over cake batter. Press crumbs down lightly to help them adhere.


Bake cake in preheated 350° oven for 45 minutes or until tester inserted into center comes out clean. Cool cake in its pan for 15 minutes. Using parchment overhang as handles, lift cake out of the pan onto a cooling rack. Once completely cool, gently remove parchment¹ and cut cake into 9 squares.

Serve and Store:

If desired, sprinkle with powdered sugar just before serving. Cake will keep well at room temperature for a few days covered with plastic wrap, or you may freeze individually wrapped pieces for several months, remove from freezer several hours (or the night before) before serving.


¹ The best way I’ve found to do this is to place the bottom of the pan used to bake the cake on top of the crumb part. Hold pan and cooling rack and quickly flip the cake over. Remove cooling rack, gently peel parchment off the bottom of the cake, and replace the cooling rack. Flip over, holding the rack and pan as before. Ta dah — minimal crumb loss and an unbroken cake!

Marble Crumb Cake (Gluten-free), from the top

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