Pre heat the oven 180 C/350 F/Gas Mark 4.

For the base

Sift the flour sugar and cocoa into a bowl. Add the butter cut into small pieces and rub into the flour until like breadcrumbs Stir in the eggs and mix with a fork to form a soft dough. Wrap in cling film and chill for an hour.

Grate the dough using a coarse grater and press across the base and up the sides of the flan tin. Scatter the base with chopped ginger and chill for 20 minutes.

Melt the chocolate over a saucepan of hot water until melted, remove the bowl from the heat. Beat the eggs in a bowl. Place the milk and cream in to a saucepan and bring to the boil. Using a whisk pour the milk on to the eggs whisking all the time and whisk in the chocolate.

Remove the pastry shell from the refrigerator place on a baking sheet and pour the custard into the shell. Bake in the oven for 10 minutes then reduce the oven to 150 C/300 F/Gas mark 2 for 10 minutes then turn the oven down to 110 C/230 F/Gas ¹⁄₄ for 30 minutes then turn the oven of and leave until almost set cool on a wire rack.

For the ganache

Melt the butter and chocolate over hot water, stir and leave until cool.

Whisk the cream in a bowl until softly peaking and add the chocolate and ginger syrup mix until evenly blended. Spread the mixture over the tin and chill.

Just before serving drag a dessert spoon over the ganache to form curls. Arrange on top of the tart and dust with icing sugar.