Preheat oven to 350°F. Microwave chocolate and margarine in large microwaveable bowl on HIGH 2 min.or until margarine is melted. Stir until chocolate is completely melted. Add SPLENDA® Granular and granulated sugar; mix well. Add eggs, 1 at a time, beating with electric mixer on low speed after each addition until well blended. Add vanilla; mix well. Add 1/2 cup of the flour, the baking soda and salt; mix until well blended. 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 28 to 30 min. or until toothpick inserted in centers comes out clean. Cool 10 min.; remove from pans to wire racks. Cool completely. Fill and frost with Chocolate Cream Cheese Frosting Sweetened with SPLENDA®. Store in refrigerator.