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Rhubarb & Buckwheat Crumb Cake
recipe
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Chicago
Rhubarb & Buckwheat Crumb Cake
Martin Sorge
Martin Sorge
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$1.00
Otherwise known as Rhabarberbuchweizenstreuselkuchen. A scrumptious, gluten-free cake made with earthy buckwheat and zippy rhubarb, perfect next to a bowl of morning yogurt and hot coffee. Makes one 9-inch square cake, about 9-16 servings.
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You Need

9-16 servings
2:00

  • Crumble (AKA Streusel)

    • 200 g buckwheat flour
    • 80 g sugar
    • 3/4 teaspoon fine sea salt
    • 113 g (1 stick) unsalted butter, melted
    • 1 teaspoon vanilla extract
    • 1 egg white
    • 2 tablespoons whole buckwheat groats

  • Rhubarb

    • 400 g rhubarb, trimmed
    • 1 Tablespoon sugar (or 1 Tablespoon vanilla sugar)
    • 1 Tablespoon buckwheat flour
    • 1/8 teaspoon fine sea salt

  • Cake

    • 180 g sugar
    • 1/2 teaspoon fine sea salt
    • 180 g buckwheat flour
    • 60 g almond flour
    • 2 teaspoons baking powder
    • 100 g (7 Tablespoons) unsalted butter, melted
    • 30 g (3 Tablespoons) olive oil (or any neutral-flavored oil)
    • 3 large eggs, room temperature
    • 2 teaspoon vanilla extract
    • 80 g Greek-style yogurt (full-fat is best, but any will do)

    • How To

    1. Butter a 9-inch by 9-inch square metal baking pan and line it with parchment paper.
    2. Make the crumble top: Whisk together the buckwheat flour, sugar, and salt. Add the vanilla extract to the melted butter and stir. Pour the butter mixture into the dry ingredients. Stir to combine until it starts to form clumps. Get in there with your hands to finish stirring and squeeze some of the mixture into bigger clumps. Refrigerate until needed. (You can make this part up to a day ahead of time.)
    3. Wash the rhubarb, dry it, then chop it into 1/2-inch chunks, set it aside in a bowl.
    4. In a large mixing bowl, add the sugar, salt, buckwheat flour, almond flour, and baking powder. Whisk it all to combine. Add the melted butter, olive oil, beaten eggs, vanilla extract, and Greek yogurt, then whisk to thoroughly combine (no lumps, please!). There's no gluten here, so you can't over-mix. Pour the batter into the prepared pan and spread it into an even layer.
    5. Toss the chopped rhubarb with 1 Tablespoon sugar, 1 Tablespoon buckwheat flour, and a pinch of salt. Evenly distribute the rhubarb on top of the cake batter. Sprinkle any leftover sugar or flour on top of the rhubarb. Do not push the rhubarb down; let it sit on the top as much as possible.
    6. Beat one egg white with a fork until foamy, and stir this gently into the streusel mixture. Get in there with your hands and toss the egg white thoroughly. Squeeze the mixture together so that there are some bigger chunks. Sprinkle the streusel evenly on top of the cake. Shower on the buckwheat groats for some added crunch.
    7. Put the cake on the middle rack of the oven and bake at 350°F for 50-60 minutes until it feels quite firm when pressed in the center and a toothpick inserted in the center comes out with just a few crumbs attached (no wet batter). Let cool for at least 30 minutes in the pan before serving.
    8. This cake is best the day it's made or the following day.