Tiramisu Cake

Tiramisu meaning 'Pick me up'.Breaking the rules slightly I've used a french sponge mixture (Genoise) in a typically Italiano dessert. I know Rome will never have me again but I prefer a more avant garde approach to cooking.
Rich, creamy, sweet, bitter and will have you up awake in the middle of the night in a sweat panting.


SPONGE:
150g plain flour
150g caster sugar
3 large eggs
60g butter
1 teaspoon baking powder

CHEESE FILLING:
3 egg yolks
80g sugar
2 tablespoon water
250ml double cream
400g mascarpone

COFFEE SYRUP:
200ml coffee espresso shots
125ml Kahlua
75g sugar
1 teaspoon vanilla extract

GARNISH:
50g bitter dark chocolate
1/2 teaspoon dark cocoa powder

METHOD:
To make the sponge grease 2 sandwich cake tins 20cm diameter with butter and then line the base and sides seperatly with parchment paper, pre-heat the oven to 180oC.
Place a small pot of water on medium high heat and bring to boil. In a large stainless steal or glass mixing bowl crack the eggs and add the sugar, beat together till evenly combind and place over boiling water turn the heat down to medium. Beat the eggs and sugar together over the heat till the mixture has quadrupled in voloum and is a pale creamy colour then remove from heat and keep beating till the mixture has cooled down completely (use a eletric beater if you're struggling with a whisk and arm action). Place the butter in a small sauce pan and melt over a high heat till it turns nutty and brown then remove from the heat to cool slightly. Sieve the flour and baking powder together then using a metal spoon gently fold the dry mixture into the eggs a third at a time till just under combined then carefully fold in the butter till just mixed. Divide the sponge mixture evenly between the sandwich cake tins and bake in  oven on middle shelf for 15 minutes. Once cooked the sponges will be slightly springy to the touch, leave to cool for 10 minutes before tipping out of the tin.
Now make the coffee syrup, pour the coffee and sugar in a small pot and place on a low heat and stir till the sugar has dissolved then take off heat and add the Kahlua and vanilla put aside to cool.
To make the cheese filling beat together the yolks, sugar, water and 2 tablespoons of the coffee syrup in a medium stainless steal or glass mixing bowl and place over a small pot of simmering water. Whisk till pale and creamy should take around 8-10 minutes,  remove from heat and leave to cool completely.
In a large mixing bowl whisk the cream till just whipped and slightly floppy then fold in the mascarpone and finally mix in the cooled yolk mixture a third at a time till just incorporated.
Length ways cut the sponges evenly in half.
To construct the tiramisu place one slice of the sponge on a serving plate and drizzle a 8th of the coffee syrup over the sponge. Followed by spooning a quarter of the cheese filling into the center of the sponge and gently spread over the surface till 1cm from the edge, dribbled a few drops of coffee syrup over the cheese filling, repeat this process 3 more times.
To garnish melt the dark chocolate and drizzle in circles over the top of the tiramisu then using a small fine sieve tap the cocoa powder over the surface of the tiramisu and place in fridge for at least an hour to set before serving.