preheat oven to gasmark 5 or 375°F fahrenheit or 190°F celsius

grease cake tin with butter

mix together the melted butter, the crushed biscuits and demerara sugar

spoon it into the bottom of the cake tin and flatten it down

to make the filling, take a small saucepan filled with water 5cm deep. bring to the boil on the hob

place a heatproof mixing bowl inside the saucepan break the chocolate into the bowl and stir it with the butter and both teaspoonfulls of boling water

remove the bowl from the heat and beat in the single cream and muscavodo sugar.whisk in the eggs quickly to avoid scrambling them

pour the mixture into the cake tin on top of the crumb base. bake for an hour and a quarter or until the top is slightly crunchy.

allow to cool before carefully removing the cake from the tin. Serve with a big squirt of whipped cream. Yum!