This is a rich delicious chocolate cake with a marshmallow type of frosting, drizzled in chocolate sauce. This cake is best served the same day it is made.
Preheat oven to 350F.
Cut parchment paper rounds to fit two 8x2 inch round cake pans. Grease with butter and dust with cocoa powder.
Place the pans onto a baking sheet.
Cake:
In the top of a double boiler or a small saucepan over low heat, melt the chocolate and set aside.
In a mixing bowl, sift together the flour, cocoa, baking soda, baking powder and salt.
In a large mixing bowl, using an electric mixer on medium speed, cream the butter until soft and creamy.
Beat in the sugar and add the eggs, one at a time, mixing until well combined.
Beat in the vanilla.
Reduce the mixer speed to low and mix in the melted chocolate.
When chocolate is fully incorporated, add the dry ingredients alternately with the buttermilk, adding the dry ingredients in 3 additions and the milk in 2 additions.
Scrape down the sides of the bowl as needed and mix only until the ingredients disappear into the batter.
The batter will be thick, like frosting.
Still working on low speed, mix in the boiling water.
This will thin the batter considerably.
Switch to a rubber spatula, scrape down the bowl and stir in the chopped chocolate or chocolate chips.
Divide the batter evenly into the prepared pans and flatten the tops with the rubber spatula.
Place into the preheated oven and bake for 25 to 30 minutes, rotating the pans at the midway point.
Cakes are baked when they are springy to the touch and a toothpick inserted into the centers comes out clean.
Remove from the oven and place the cake pans on racks to cool for about 5 minutes.
Run a knife around the sides of the cakes,and turn the cakes out onto the racks.
Peel off the paper liners.
Invert and cool to room temperature right side up.
When you are ready to fill and frost the cake, cut the crowns off the tops to make flat cakes using a long serrated knife with a sawing motion.
Set the crumbs aside to use later.
Do not frost until cooled completely.
Filling and Frosting:
You will need a candy thermometer at the ready.
Put the egg whites into a clean, dry mixing bowl.
Put the sugar, cream of tartar and water into a medium saucepan and stir to combine.
Bring the mixture to a boil over medium-high heat.
Cover with a lid and let boil for 3 minutes.
Uncover and allow the syrup to boil until it reaches 242F. on the candy thermometer.
While the syrup is cooking, start beating the egg whites.
When the syrup reaches 235F., begin beating the egg whites with and electric mixer on medium speed.
If the whites form firm, shiny peaks before the syrup reaches temperature, reduce the mixer speed to low and keep mixing the whites until the syrup catches up.
With the mixer at medium speed, carefully pour in the hot syrup, pouring it between the beaters and the side of the bowl.
Splatters will happen but don't try to scrape them into the whites, just carry on.
Add the vanilla extract and keep beating the whites for about 5 minutes at medium speed until they reach room temperature.
You should have a smooth, shiny, marshmallow type frosting.
Chocolate Drizzle:
Place the cream and chocolate in a double boiler over hot but not boiling water. Heat for 3-4 minutes or until chocolate almost melts, stirring occasionally.
Remove from the heat and use a rubber spatula to stir until all the chocolate melts.
Let the chocolate cool to room temperature before using.
Assembly:
Put one layer of cake on a cake plate.
Cover the layer generously with frosting.
Top with a second layer and cover the entire cake with frosting on the top and sides and use a metal cake spatula to make swirls as you frost.
Sprinkle the chocolate cake crumbs on, gently pressing the crumbs into the filling with your fingers.
When you cut and serve the cake, drizzle chocolate on and garnish with a chocolate mint cookie if desired.
The frosting used in this recipe is best the same day it is made.