8 ounces beets, unpeeled, rinsed and scrubbed free of dirt
7 ounces bittersweet or semisweet chocolate, chopped
1/4 cup hot espresso
7 ounces butter at room temperature, cubed
1 cup flour
3 tablespoons unsweetened cocoa powder
1 1/4 teaspoon baking powder
5 large eggs, separated, at room temperature
Pinch salt
1 cup sugar
Grease an 8 1/2 inch pan and line the bottom with parchment paper. Boil the beets in salted water until very tender, about 45 minutes. Drain, then rinse with cold water. When cool enough to handle, slip off the peels, cut into chunks, and grind in a food processor or grate until a coarse puree.
Preheat the oven to 350ºF. In a large bowl, set over a pan of barely simmering water, melt the chocolate, stirring as little as possible. Once melted, turn off the heat, pour in hot espresso and stir once. Press butter pieces into chocolate and allow to soften without stirring.
Sift together flour, cocoa powder, and baking powder in separate bowl. Remove bowl of chocolate from heat and stir until butter is melted. Let sit to cool, then stir egg yolks together and briskly stir them into chocolate mixture. Fold in the beets.
In stand mixer, or by hand, whip egg whites until stiff. Gradually fold sugar into egg whites, then fold into melted chocolate mixture, being careful not to overmix. Fold in the flour and cocoa powder.
Scrape the batter into prepared cake pan and reduce oven heat to 325ºF, and bake for 40 minutes, or until sides are just set but center is still is wobbly. Do not overbake. Let cool completely, then remove from pan.
Spread with crème fraîche and sprinkle with poppy seeds shortly before serving.
We thank davidlebovitz.com for this recipe.