MICROWAVE chocolate and butter in large microwaveable bowl on high 2 minutes or until butter is melted. Stir until chocolate is completely melted.
STIR in sugar until well blended. Add eggs, 1 at a time, beating with electric mixer on low speed until well blended after each addition. Stir in vanilla. Add 1/2 cup of the flour, baking soda and salt; mix well. Add remaining 2 cups flour alternately with water, beating until well blended after each addition. Pour evenly into 2 greased and floured 9 inch round cake pans.
BAKE at 350 degrees F for 35 mins or until toothpick inserted in centers comes out clean. Cool 10 mins.; remove from pans. Cool completely on wire racks. Fill and frost with BAKER'S ONE BOWL Chocolate Frosting.