Step 1Heat the oven to 350 degrees. Grease and flour three 9-inch round cake pans.
Step 2Place the cocoa in a small mixing bowl and pour 2 cups boiling water over it. Stir well with a fork until smooth, and set aside to cool.
Step 3Put the flour, baking soda, baking powder and salt in a medium bowl and stir with a fork to mix well. Set aside.
Step 4With a mixer, beat the butter and sugar at high speed until well combined. Add the vanilla and then the eggs, one at a time, beating well after each until the mixture is smooth and light.
Step 5Add the flour mixture in four batches, beating after each addition only until the flour disappears. Alternate with the cocoa mixture in three batches, beating after each just enough to combine everything into a smooth, luscious batter, stopping once or twice to scrape down the sides of the bowl.
Step 6Divide the batter among the three cake pans. Bake until the cakes spring back when touched lightly in the center and are beginning to pull away from the sides of the pans, 25 to 30 minutes.
Step 7Place the cake pans on wire racks and cool the cake layers for 10 minutes. Then gently turn them out onto wire racks to cool completely, top side up.
Step 1In a mixer bowl, combine the cream, sugar and vanilla and beat until thick and luscious. Cover and refrigerate until you are ready to complete the cake.
Step 1In a medium saucepan, combine the chocolate bits, cream and butter. Cook gently over medium heat, stirring often to help the butter and chocolate to melt, and to avoid letting the mixture come to a boil. When the chocolate and butter have melted, transfer the mixture to a medium bowl and allow it to come to room temperature. Add the powdered sugar and beat well at medium speed until thick enough to spread, stopping often to scrape down the bowl.
Step 2To complete the cake, place the first layer, top side down on a serving plate and spread half the whipped cream filling almost to the edge. Cover with a second layer, top side down, and spread the remaining whipped cream filling. Place the third layer, top side up, over the filling. Spread the chocolate frosting over the sides and then top of the cake.