Rather than add flavor of their own, the puréed beets in this recipe provide moisture and enhance the rich chocolate in this cake. The vermouth-jam adds a nice sweet and spicy counterpoint to the cake's layers.
For the cake
4 medium beets, trimmed, peeled, and cut into 2-inch chunks
2 cups all-purpose flour
1 1/2 cups sugar
1/2 cup unsweetened cocoa powder
1/4 teaspoons baking soda
2 large eggs
3/4 cup warm water
1/4 vegetable oil
For the jam
1 cup of raspberry jam
1/2 cup sweet vermouth
1/2 cup fresh raspberries
Preheat your oven to 350 degrees. Cover beets with 2 inches water in a pot and bring to a boil. Reduce the heat, and simmer until the beets are very tender when pierced with the tip of a sharp paring knife, about 30 minutes. Drain and puree the beets in a food processor until smooth.
Whisk together flour, sugar, cocoa powder, baking soda, and 3/4 teaspoon salt in a large bowl. Whisk in eggs, water, oil, vanilla, and 1 1/4 cups beet puree (reserve remaining puree for another use).
Coat a 9-inch round cake pan (3 inches deep) with cooking spray. Line bottom with parchment, and coat with spray. Pour batter into pan. Bake until a toothpick inserted into the center comes out clean, about 45 minutes. Let cool in pan on a wire rack for 20 minutes. Turn out cake from pan, and discard parchment. Let cool completely, right side up.
Meanwhile, add the vermouth to a small pot and bring to a simmer over medium heat. Simmer the vermouth until it is reduced by half. Add the jam and cook until the mixture is slightly thickened, about 15 minutes. Remove from the heat and let cool to room temperature.
Trim top of cake using a serrated knife and cut horizontally to create two even layers. Spread the raspberry jam on the bottom layer of the cake and top with the second top.