Preheat the oven to 180C. Prepare a 23" springform pan.
Melt the white chocolate, either in a double boiler or in the microwave.
Pour over the softened butter and gently mix until no lumps remain.
Place the 2 whole eggs and the 4 egg yolks into a bowl and mix with 75g of the sugar until all combined.
Gently mix the chocolate mixture into the egg and sugar mixture.
Whisk the egg whites until foamy and then add the remaining 100g sugar until soft peaks form (not stiff).
Take about a tablespoon of the egg white and sugar mixture and gently stir into the chocolate mixture. Carefully fold in the rest of the egg whites.
Pour into prepared pan and bake for 40 minutes, or until the top is browned.
Take out of the oven and leave to cool in the pan.
Recipe Notes
The top will cave in as it cools, but this is the holder for the whipped cream and other toppings, such as strawberries, grated chocolate or other decadent treats.