Chocolate Buckwheat Cake

 

I found this chocolate buckwheat cake quite unusual in that it is made with a yeast sponge. In fact, the sponge and whipped egg whites are what hold it together, as it is gluten-free. It is pleasantly dense, and I think there’s a range of “ready” textures – from slightly fudgy for a lesser baking time to more crumbly for a longer one. This was a hit with my family! 

For the sponge 

1 tsp. instant yeast 

½ cup (63 g.) dark buckwheat flour 

1 Tbsp. honey (buckwheat if you have it) 

For the cake 

4 large eggs 

¾ cup (135 g) bittersweet chocolate chips 

½ cup (1 stick) lactose-free butter, cut into pieces 

¼ cup (25 g) Dutch-processed cocoa powder, sifted 

1 Tbsp. vanilla extract 

1 pinch of kosher salt 

½ cup (100 g) granulated sugar, divided 

2 Tbsp. powdered sugar 

For the sponge 

Place ¾ cup lukewarm (98 °F–105 °F) water in a medium bowl and sprinkle yeast over. Whisk in buckwheat flour and honey. Cover with a kitchen towel or plate. Let sit at room temperature until surface of sponge looks frothy with big and small bubbles across the top, about 1 hour. 

For the cake 

Place a rack in middle of oven; preheat to 350 °F. Coat a 9” springform pan with nonstick spray; line it with paper, and coat again. 

Separate yolks from eggs over a large bowl to catch egg whites. Place yolks in another small bowl; set egg whites aside. 

Combine chocolate and butter in a medium heatproof bowl and set over a medium saucepan of simmering water (do not let bowl touch water). Melt chocolate, stirring occasionally, until smooth. Remove from heat and whisk in cocoa powder, vanilla, salt, and ¼ cup (50 g) granulated sugar. Add egg yolks one at a time, whisking until smooth after each addition. Stir in sponge. 

Add remaining ¼ cup (50 g) granulated sugar to bowl with reserved egg whites. Using an electric mixer on medium-high speed, beat until soft peaks form, about 4 minutes. Fold half of egg whites into batter until smooth, then fold in remaining egg whites until just combined. Scrape batter into prepared pan and smooth surface. 

Bake cake, rotating pan halfway through, until a tester inserted into the center comes out clean, 40–45 minutes. Let cake cool in pan. Run a paring knife around edges of cake, then unmold and place on a plate. Dust with powdered sugar just before serving.