- Preheat oven to 180 degrees celsius. Sift the flour, cocoa powder and salt together. In a bowl, cream the butter and sugar until pale and fluffy. Mix in the melted chocolate and whole egg.Combine with the dry ingredients and knead lightly to smooth dough. It will be a bit dry but don't worry about it. Shape into a flat disk and refrigerate for at least 20 minutes.
- Spray and flour a 20cm flan tin. Place the pastry onto a lightly floured service and roll out to about 3mm thick and so that the pastry will overhang the top of tin. Chill again for 20 minutes. Prick the pastry base and blind bake for 10-15 minutes. Leave the pastry to cool completely (may need to put back into refrigerator).
- Meanwhile, melt the remaining dark chocolate over a bain marie. Bring the cream, milk and vanilla bean to the boil and slowly combine with the melted chocolate. Fold in the cocoa nibs. Keep stirring. Whisk together the eggs and sugar. Combine with the chocolate cream.
- Place the cool pastry flan tin on a baking sheet in the middle oven shelf. Pour the chocolate filling into the tart case. Bake for 35 minutes until set. Allow to cool. Sprinkle some extra cocoa nibs on top and serve when completely cooled.