In a large bowl, combine the first 7 ingredients; beat on low speed for 30 seconds. Beat on medium for 2 minutes. , Pour into a well-greased 10-in. fluted tube pan. Bake at 350° until a toothpick inserted near the center comes out clean, 50-55 minutes. Cool for 10 minutes before removing from pan to a wire rack to cool completely., In top of a double boiler, melt butter and chocolate. Stir occasionally until mixture is glossy and smooth. Drizzle over cake.