First prepare the pastry: Place the butter and sugar in a food processor and process until just combined. Add the eggs and continue processing for 30 seconds. Add the flour and process for a few seconds until the dough just comes together, (add 1 tbsp cold water if the dough seems too dry).
Remove the dough and Knead lightly on a surface dusted with flour. Shape it into a flat disc and refrigerate for at least 30 minutes.
Preheat the oven to 190oC. Remove the pastry from the refrigerator and line it in a 20cm loose-based tart in or tart ring. Leave some excess pastry hanging over the edge. Refrigerate again and let it rest for 20 more minutes. Line the pastry with foil or baking parchment and fill with beans. Bake the pastry for 15 minutes, until the sides just begin to colour. Remove the beans and foil and bake for another 5 more minutes or until the base is cooked and lightly golden.
Remove the pastry from oven, brush the base with the melted chocolate and let it cool to room temperature. Lower oven to 110oC.
Lemon Cream: Stir the eggs, yolks and sugar together in a bowl and combine with the cream. Finally, add the lemon juice - this will thicken the cream.
Strain the filling through a fine sieve into a jug. Pour the filling into the pastry case and put the pastry case onto the bottom oven shelf. Carefully push the shelf back and bake for 50-60 minutes until the filling is almost set. It should have a slight wobble in the centre. Trim the pastry level with the top of the tin and leave it to cool completely.
Dust with icing sugar and run a cook's blowtorch over the surface to create a caramel crust.