For the marmalade: Cut the oranges and lemon in half, then cut the halves into very thin slices. Place the slices in a large nonstick or stainless-steel pot, add 4 cups water, and bring to a boil. Remove the pan from the heat and add the sugar, stirring well until the sugar is dissolved. Cover the pan and refrigerate overnight.
The following day, bring back to a boil, reduce the heat, and simmer for 2 hours. Turn up the heat a little and boil gently for another 30 minutes. Place a candy thermometer in the marmalade and cook until it reaches the jelly stage (220 degrees F).
For the cake: Preheat the oven to 350 degrees F. Spray two 8-inch round cake pans with nonstick baking spray.
Melt the butter and chocolate in an 8-cup microwave-safe container. Whisk in the sugar and then the cocoa powder until fully incorporated. Slowly add the hot coffee in three increments, whisking until smooth. Add the vanilla, then add the eggs, one at a time.
Combine the flour, baking soda, baking powder and salt in the bowl of a stand mixer fitted with the whisk attachment; mix until combined. With the mixer on low speed, gradually pour in the chocolate mixture; beat on medium-high speed for 1 minute. Scrape the bottom of the bowl and beat until smooth, another 30 seconds.
Pour the batter into the prepared cake pans. Bake for 35 to 40 minutes. Cool on a baking rack.
For the buttercream: Set a clean stand-mixer bowl over a double-boiler and add the egg whites and sugar. Whisk until the sugar is completely dissolved. Transfer the bowl to the mixer and beat with the whisk attachment until stiff and glossy. Piece by piece, gradually incorporate the butter--the mixture will start to look curdled but will come together once fully incorporated. Add the melted chocolate, cocoa powder, orange zest and vanilla; beat until incorporated.
To assemble: Level the cooled cake layers and lightly brush with the orange liqueur. Spread the top of each layer with a thin layer of marmalade and then, using an offset spatula, with the buttercream cream. Stack the cake layers.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.