For the filling melt the Toblerone in a bowl over a pan of simmering water and then stir in the light muscovado sugar and dissolve any lumps in the sugar then set aside to cool for 5 minutes. In a small bowl, mix the cocoa powder with 3 tbsp. of hot water until it is smooth.
In a large bowl, whip the cream until it holds its shape, and then carefully fold in the cooled, melted Toblerone mixture and the cocoa mixture.
In another large bowl, gently beat the cheese until it is soft.
Finally combine the cheese with the cream and chocolate mixture.
Pour into the tin onto the chilled base. Chill overnight in the fridge until set.