• Preheat oven to 350°F (180°C). Liberally grease two 8" round cake pans with vegetable shortening, and/or spray with baking spray.
• Combine flour, cocoa, sugar, baking powder, salt, and pudding mix in a large mixing bowl. Add in eggs and water, beating until smooth. Carefully add melted butter and vanilla to the mix, mixing on medium speed until smooth.
• Divide batter among prepared cake pans. Bake until golden and knife inserted into center of batter comes out clean and cake springs back - about 45-60 minutes. Allow to cool 10-15 minutes before turning cakes out onto baking rack to cool fully. Ideally, allow to cool to room temperature, wrap tightly with plastic wrap. Allow cake to sit overnight.
• Prepare Swiss meringue buttercream as described in recipe. Add blood orange essential oil and food coloring, if using. Continue to mix until well incorporated.
• Place chocolate chips into a glass mixing bowl, and put aside. In a small saucepan, combine heavy whipping cream, essential oil, butter, and sugar. Heat to a boil, remove from heat. Pour hot cream mixture into bowl of chocolate chips. Let sit for 3-5 minutes. Starting in the middle of the bowl, slowly start stirring the chocolate and cream until all of the chocolate is melted and the cream has disappeared into it - it should be smooth.
• Cover with plastic wrap, allow to cool to room temperature. Using a stand or hand mixer, whip for 2-3 minutes until fluffy.

To assemble cake:

• Remove plastic wrap from cake layers. Carefully slice the domed top off each round, leveling the surface of the cake. Carefully cut each cake in half, horizontally, for 4 thin rounds of cake in all.
• Place one round of cake on cake plate, spread with a thick layer of chocolate ganache. Top with a second round of cake, spread with a thick layer of blood orange buttercream. Top with a third round of cake. Spread with a final thick layer of chocolate ganache, and top with remaining layer of cake. Smooth out any frosting or ganache that may have bulged from between cake layers.
• Chill for 30 minutes before frosting sides and top of cake with remaining buttercream. Serve at room temperature.