To make the pastry, put the flour, sugar and a pinch of salt in a large mixing bowl and stir together with a spatula. Add the diced butter. Then wash your hands in cold water and dry them. Then rub the butter into the dry ingredients taking care not to over mix or the butter will break down the pastry will be oily and difficult to roll. Make a well in the centre of the mixture, add the egg yolks and mix them in with a spatula until it comes together. Finish by pushing everything together into a dough and DON’T OVER HANDLE! Shape into a flattened disc, wrap in clingfilm and chill for about an hour, until pliable but not sticky to the touch.
Preheat the oven to 190C/180C Fan/Gas 5. Roll out the pastry until about ½cm thick, and use to line a greased 22cm fluted tart tin. Refrigerate until firm, then line with greaseproof paper and baking beans, and blind bake for about 15 minutes until golden. Put the tart tin on a flat baking tray to make it easier to move the tin in and out of the oven. Then remove the paper and beans and brush the base with egg white. Put back in the oven for another 8 minutes, then remove, turn off the oven and leave to cool.
Measure all the filling ingredients into a bowl and whisk until smooth. Carefully pour the filling mixture into the cold baked pastry case.
Transfer the tart and tray carefully to the oven and bake for 35-40 (20 minutes for small tarts) minutes or until just set but still with a slight wobble in the middle. The filling will sink down a bit when it has cooled.
Leave to cool a little, or completely, and then remove it from the tin. Transfer to a serving plate and dust with icing sugar to serve.
For the pastry
For the filling