The Perfect Chocolate Cake!
Preheat oven to 350 F. Grease the bottoms of 3 - 9 inch round cake pans and line with parchment or waxed paper (cut to fit) and then grease over the paper and on the sides of the pans. Set aside.
In a medium-sized bowl, combine the cocoa with the boiling water. Using a whisk, mix well until smooth. Cool completely.
In another bowl, combine the flour, baking soda, salt, and baking powder. Stir several times with a whisk (this is very similar to sifting the ingredients) and set aside.
In a large mixing bowl, beat the butter and sugar until light and fluffy; about 5 minutes. Add the eggs, one-at-a-time, mix well and then add the vanilla. At low speed, mix in the flour mixture in fourths with the cocoa mixture in thirds (begin with the flour and alternate with the cocoa mixture, ending with the flour mixture). Do not overbeat.
Divide the batter evenly between the 3 prepared cake pans. Bake for 25 - 30 minutes or until the center of the cake springs back when touched and the cake begins to pull away from the sides of the pan. Cool in the cake pans for 10 minutes; remove from the pans and cool completely on racks.
In a medium-sized saucepan, combine the chocolate chips, cream, and butter and cook over medium-low heat until the butter melts and the mixture is smooth. Remove from heat and let cool for 15 - 30 minutes. Stir ocassionally.
In a large bowl, combine the powdered sugar and the chocolate mixture. Stir well with a whisk until all the powdered sugar has been incorporated. Using a mixer, beat the frosting until it holds its shape, about 10 - 15 minutes. Set aside.
In a medium-sized bowl, whip the cream, powdered sugar, and vanilla until stiff peaks form.
Place several small sheets of waxed paper around the outside edge of your serving plate and center the first layer over these sheets. This helps to keep any spilled frosting off your serving plate.
Place the first cake layer (top side-down) on a cake or serving plate. Fill a piping bag fitted with a round tip with about 1/4 - 1/2 cup buttercream frosting and pipe a wall (dam) around the outside edge of the cake. Put half of the cream filling on the inside of the wall.
Place the second later (right side-up) on the first layer, taking care to center. Follow the same procedure as above for piping a wall of buttercream and adding the rest of the cream filling.
Place the third layer (top side-down) on the second layer. I like to start with the top of the cake when frosting and then do the sides, but you can use whatever method works best for you. Carefully remove the waxed paper sheets from around the edge of the cake, if you used them.
Refrigerate the cake for at least one hour before serving and store it in the refrigerator.