Use a 23 cm ( 9-10 in) tart case with a removable bottom.
Preheat the oven 180 C (350 F)
Put the flour, sugar & butter into the food processor and blitz till combined ( breadcrumb texture). Mix the water and egg well in a cup then add 3/4 of it to the flour mix. Turn on the machine and watch till it starts to come together, if it stays quite crumbly then add the rest of the egg till the mixture forms a ball.
Tip out onto a bench, wrap and chill, till firm.
Roll the pastry out quite thinly between two pieces of baking paper making sure to use extra flour to prevent sticking and tearing. One in the tin trim, then chill again till firm ( freezer is good)
Bake the pastry blind in a 180 C(350 F) oven for 15 minutes then remove the weights and bake till golden ( approx another 15 min) .
Meanwhile beat the eggs, yolks ,sugar and vanilla until very light and fluffy. Add the mascarpone and cornflour and beat till combined and fluffy .
Fold the raspberries into the mixture with a spatular and pour into the tart case.
Bake on 160 C (320 F) for 35-40 minutes or until set and just a bit wobbly.
Cool, then refrigerate to set completely