Preparation Preheat oven to 275°F. Butter springform pans and line bottom of each with a round of wax paper. Butter paper and dust pans with flour, knocking out excess. Wrap bottom and 1 inch up side on outside of each springform pan with foil (to catch drips). Melt chocolates and butter with coffee in a 4-quart saucepan over moderately low heat, stirring constantly until smooth. Remove from heat and cool 10 minutes. Beat in bourbon, eggs, and vanilla. Sift in flour, sugar, baking soda, and salt and stir until batter is smooth (batter will be thin). Divide batter between springform pans (about 3 cups batter in each). Bake cakes in middle of oven 1 to 1 1/4 hours, or until a tester inserted in centers comes out with crumbs adhering. Remove from oven and cool in pans on racks 20 minutes. Run a thin knife around edge of each pan, then remove sides. When cool, remove pan bottoms and wax paper.
Preparation Preheat oven to 275°F. Butter springform pans and line bottom of each with a round of wax paper. Butter paper and dust pans with flour, knocking out excess. Wrap bottom and 1 inch up side on outside of each springform pan with foil (to catch drips). Melt chocolates and butter with coffee in a 4-quart saucepan over moderately low heat, stirring constantly until smooth. Remove from heat and cool 10 minutes. Beat in bourbon, eggs, and vanilla. Sift in flour, sugar, baking soda, and salt and stir until batter is smooth (batter will be thin). Divide batter between springform pans (about 3 cups batter in each). Bake cakes in middle of oven 1 to 1 1/4 hours, or until a tester inserted in centers comes out with crumbs adhering. Remove from oven and cool in pans on racks 20 minutes. Run a thin knife around edge of each pan, then remove sides. When cool, remove pan bottoms and wax paper.