1 Cream the icing sugar and butter together for a few minutes until light in colour. Add the flour and scrape down the sides of the bowl before adding the three whisked eggs - a little at a time - to make a soft, wet paste. Chill for 20 minutes then roll out and line your pastry case and allow it to rest for a further 20 minutes in the fridge.
2 Remove from the fridge and cover the pastry with greaseproof paper or a triple-layer of clingfilm, add baking beans and bake at 180C/Gas Mark 4 for 35 to 40 minutes, until just golden and crisp. Remove the baking beans and greaseproof paper.
3 Warm the cream and the milk together in a pan until it nearly comes to a boil. Then remove from the heat and add the chocolate. Mix well with a whisk, and then allow it to cool gently for 5 minutes or so.
4 Add three whole eggs to this mixture one at a time, stirring gently as you do. Then pour into the blind-baked tart shell and bake for 20 to 30 minutes until there is no wobble when you gently shake the tray.
5 Remove from the oven and allow to cool slightly before removing carefully from the tin. Dust with cocoa powder (optional). Cut into slices and serve with crème fraîche.
(A top tip is to use a sharp, hot, wet knife to cut the tart into perfect slices).