For this you could use ready-rolled shortcrust pastry, or make your own using your favourite recipe.
Line a 23 cm loose-bottomed tart tin with the pastry, prick the base all over with a fork and chill for 30 minutes.
Meanwhile, cut rhubarb into 4-5 cm pieces and put into an oven-proof dish. Sprinkle with 2 -3 Tbs golden caster sugar,
cover with aluminium foil and bake for 20-25 minutes in a 200°C oven, until just tender and still holding its shape.
Drain the liquid and set the rhubarb aside. Cover the pastry shell with a piece of baking parchment and fill with
baking beans. (Note: if you crumple the parchment into a tight ball and then unfurl, it will fit into the shell much
more easily.) Bake blind for 15 minutes, then remove the beans and parchment and bake for a further 5 minutes,
until just cooked. Brush the base with egg white to seal. Reduce the oven temperature to 170°C. Mix 200g sugar
with a Tbs cornflour and beat in 2 large eggs, then add 300ml crème fraîche and a tsp of vanilla essence. Arrange
the rhubarb in the base of the pastry case and pour over the custard mixture. Bake in the oven for 30 minutes,
until just set in the middle. Cool before serving.