Directions: Preheat oven to 350°. Spray a 9"x9" cake pan with butter-flavored cooking spray. Sprinkle 2 Tsp. baking mix into prepared pan. Gently pat pan to coat. In a large bowl, combine remaining 11/2 cups baking mix and SPLENDA. Add milk, egg, margarine, and vanilla extract. Mix gently just to combine. Spread batter evenly into prepared pan. Bake for 18-22 minutes or until a toothpick inserted in center comes out clean. Place pan on a wire rack and allow to cool completely. Cut into 8 servings.