Mix the almond powder and icing sugar together and add in the eggs and yolks. Add the cocoa and flour.
Beat the whites to a soft peak, add the sugar, beat to almost hard peak. Incorperate into the mix.
Chemisier (coat with butter, then coat with flour, shake out excess flour) a square pan about 8 inches or so. Bake at 375-390 till the cake is done (a toothpick comes out clean).
Boil the sugar and water together. When it starts boiling, take it off the heat and add the grand marinier.
Melt the chocolate over a bain-marie (double boiler). Add the yolks and butter, mix well. Whip the whites to soft peak, add the sugar, whip almost to hard peak. Add a small amount to the mousse and mix it in well. Add the rest and incorperate gently.
Peel the orange, saving the peel. Remove as much white off the peel as is possible and chop into small cubes 2-5 cm in length. Put in water and sugar (the amounts don't matter) and boil for 5 minutes. Throw out water, wash orange peels, and do it again untill the syrup reaches softball stage. Let sit for a long time.
Invert cake and Cut in half. Brush the syrup over the bottom and sprinkle with candied peel. Put a layer of chocolate mousse on the bottom layer. Spread syrup on inside of other half and put the top layer on.
Cover the entire cake with mousse. The top should be the flat part at this point. Decorate with mousse rosettes, sprinkle with orange peel, and put vermicelli on the sides of the cake. Vermicelli is optional.
Roll out the marzipan so that it is a long strip. Put the strip on the cake from corner to corner and write "Roy" on it with white chocolate.