Best Ever Birthday Cake

CHOCOLATE BUTTERCREAM:
1 cup butter
1 cup shortening
3 cups powdered sugar
1/2 cup cocoa powder
1/3 cup milk
2 teaspoons orange extract
3/4 cup mini chocolate chips

YELLOW LAYER CAKE:
4 cups cake flour
1 tablespoon baking powder
1/2 teaspoon salt
1/2 pound butter, softened
1 1/2 cups sugar
4 eggs + 2 yolks, well beaten
2 teaspoons vanilla
1 1/2 cups milk

GLAZE:
1 cup sugar
1 cup water
1 tablespoon rum

For Chocolate Buttercream Frosting: In the bowl of an electric mixer, blend butter, shortening and sugar with the paddle attachment until creamy. In a small bowl, whisk together cocoa powder with 3 tablespoons of hot water until smooth. Add the cocoa to the butter mixture along with the milk and extract. Continue to mix until well combined. Turn off the mixer and gently fold in chocolate chips with a spatula. Set frosting aside to firm up to a spreadable consistency.

Preheat oven to 350�F. Butter 2 (9-inch) round cake pans, including sides. Cut a sheet of parchment paper to fit the pan bottoms and lay in place. Then butter the paper and flour the entire pan. Turn the pan upside down to remove excess flour. Sift together the flour, baking powder and salt, set aside. In a large mixing bowl, cream the butter until smooth. Gradually add the sugar and beat until light and fluffy. Beat in the eggs, a little at a time. Stir in the vanilla until well blended. Scrape down the sides of the bowl. Gradually mix in the dry ingredients in 3 batches, alternating with the milk. Beat for 1 minute after each addition to incorporate the ingredients and strengthen the cake�s structure. Mix until the batter is smooth.

Pour the batter into the prepared pans and smooth the surface with a spatula, the pans should be 2/3 full. Place pans on the middle rack of the oven and bake for 20 to 25 minutes, or until a knife inserted in the center comes out clean and the cake springs back when touched. Let the cakes cool in the pans for 10 minutes, then turn them out onto a wire rack, peel off the paper and let cool for at least 1 hour. Level the tops of the cakes with a serrated knife if domed in the middle. To divide each cake in half to give 4 layers: cut a vertical notch on the side of the cakes so you can easily line up the layers when assembling. Place one hand flat on top and the serrated blade along the side of the cake. Rotate the cake against the knife as you slice. Carefully separate the layers and brush away any loose crumbs. To make sugar glaze: combine sugar, water and rum in a small saucepan. Boil for 2 to 3 minutes. Brush the sugar glaze on the cake layers to moisten and add extra flavor.

Place 2 pieces of parchment paper on the circumference of the cake plate; this will help protect the plate from smeared frosting. Put the plate on a lazy Susan; so it easier to turn and frost the cake. Lay 1 cake layer on the plate. With a metal spatula, spread about 1/2 cup of chocolate buttercream frosting on top of the base. Carefully place a cake layer on top, remember to line up the notches so it lays evenly. Do this for the remaining 2 layers.

Take a small amount of frosting, mix it with a bit of water and spread very thinly all over the cake. This wet coating will fill any cracks, secure the crumbs and seal the cake. Put the cake in the refrigerator for 10 minutes to set. With a clean, crumb-free metal spatula, spread the cake with a final attractive coat of frosting. Discard messy parchment paper, refrigerate 1/2 hour before decorating or cutting.