Cake
2 cups all-purpose flour
2 cups granulated sugar
1 cup butter
1 cup water
1/4 cup cocoa
2 large eggs, lightly beaten
1/2 cup buttermilk
1 teaspoon baking soda
1 teaspoon pure vanilla extract

Filling
1 (3 7/8 ounce) box instant chocolate pudding mix
1 1/4 cup milk
1 (8 ounce) container frozen whipped topping
    (Cool Whip), thawed

Glaze
1/2 cup butter
1/4 cup cocoa
6 tablespoons half-and-half
1 cup confectioners' sugar
1 teaspoon pure vanilla extract

Preheat oven to 350 degrees F.

Cake: Combine flour and sugar in large bowl; set aside.

Combine butter, water and cocoa in medium saucepan. Heat to a boil over medium heat, stirring frequently. Pour butter mixture over flour mixture; mix well. Stir in eggs, buttermilk, baking soda and vanilla extract.

Divide batter between 2 greased 9-inch round cake pans. Bake until wooden pick inserted in center comes out clean, 20 to 25 minutes. Cool in pans 10 minutes; turn out onto cooling rack. Cool completely.

Filling: Combine pudding mix and milk in bowl of electric mixer. Beat on high speed until thickened, 3 to 4 minutes.

Add whipped topping; beat 2 minutes. Refrigerate until set, about 5 minutes.

Glaze: Heat butter, cocoa and half-and-half to a boil in medium saucepan over medium-high heat. Remove from heat; slowly stir in confectioners' sugar (if added too fast, glaze will be lumpy). Stir in vanilla extract. ( Note: Glaze must be warm when ready to pour over cake.)

Place 1 cake round upside down onto cake platter. Top with pudding mixture, it will be a thick layer. Place second cake layer on filling. Slowly pour warm glaze over the top; allow it to run down sides. Chill 2to 4 hours before serving.