White Chocolate Fudge Cake

1 package (18-1/4 ounces) white cake mix
1-1/4 cups water
3 egg whites
1/3 cup vegetable oil
1 teaspoon vanilla extract
3 squares (1 ounce each) white baking chocolate, melted

Filling
3/4 cup semisweet chocolate chips
2 tablespoons butter

Frosting
1 can (16 ounces) vanilla frosting
3 squares (1 ounce each) white baking chocolate, melted
1 teaspoon vanilla extract
1 carton (8 ounces) frozen whipped topping, thawed

In a mixing bowl, combine the dry cake mix, water, egg whites, oil and vanilla. Beat on low for 2 minutes. Stir in white chocolate.

Pour into a greased 13-in. x 9-in. x 2-in. baking pan. Bake at 350° for 25-30 minutes or until a toothpick inserted near the center comes out clean. Cool for 5 minutes.

Meanwhile, in a microwave or heavy saucepan over low heat, melt chocolate chips and butter; stir until smooth. Carefully spread over warm cake. Cool completely.

In a mixing bowl, beat frosting; stir in white chocolate and vanilla. Fold in whipped topping; frost cake. Store in the refrigerator. Makes 16 servings.