I was pleased with the way this turned out, given it was almost completely made up. Using crème fraiche rather than cream made it really light and gave it a nice taste as well as being lower in fat. I used what i had rather than weigh things out so use this as a guide if you want to make it. Also, I used a pretty small (9 inch) enamel dish so if you want a larger one, increase accordingly.
Ingredients 2 eggs 2 large tablespoons of low fat crème fraiche about 50g butter about 50g dark muscovado sugar 100g dark chocolate ready-rolled pastry (puff or shortcrust would both work)
Grease a dish and line it with pastry. Bake blind for 10 minutes while you make the filling. (I used beans to weigh down silver foil to bake this blind). For the filling melt chocolate, sugar, and butter together in a bowl over boiling water, then add the eggs and creme fraiche. Pour into pastry case and cook for 30-40 minutes on a medium heat (Gas 4 for me) until the filling has solidified, and a fork inserted comes out clean.