1 1/2 cups all-purpose flour
1 cups sugar
1/2 cup unsweetened cocoa powder
2 teaspoons cinnamon
1 teaspoon baking soda
1/4 teaspoon cayenne pepper or chili powder
1/4 teaspoon salt
1 tablespoon balsamic vinegar
1 tablespoon vanilla extract
1 cup cold water
2/3 cup powdered sugar
1/3 cup unsweetened cocoa powder
2 or 3 tablespoons water
1. Preheat oven to 350°F.
2. In a large mixing bowl, whisk together first seven ingredients (flour through salt). Make two small wells in the mixture. In one, pour in the vinegar. In the other, pour in the vanilla extract. Pour cold water over everything. Stir until moistened and a only a little lumpy.
3. Pour batter into an 8-inch round cake pan. Bake for 30 or 35 minutes, or until a toothpick inserted in the center of the cake comes out clean. Cool for 10 minutes in the pan, then carefully pry out and finish cooling on a wire rack.
4. While cake is baking, whisk together 2/3 cup powdered sugar and 1/3 cup unsweetened cocoa powder in small bowl. Add water. Stir to make a thick glaze. When cake is completely cooled, drizzle over cake.