1 For the pastry dough: Place flour in a mound on a clean work surface, mix in the sugar and salt then make a well in the center. Cut the cold butter into small pieces and distribute around the edges. Add the cream to the well and chop all the ingredients together with a knife. With your hands, rapidly mix dough until combined, form into a ball, wrap in plastic wrap and chill for about 30 minutes.
2 For the vanilla cream: Cut the vanilla pod in half lengthwise and scrape out the seeds into a pot. Add the vanilla bean pod to the pot along with the milk and bring to a boil. Whisk the egg yolks with the sugar in a bowl until creamy then mix in the cornstarch.
3 Let the milk cool slightly, slowly stir into the egg yolk mixture in a thin stream, pour everything back into the pot, remove the vanilla pod and simmer over low heat, stirring until thickened. Do not boil!
4 Preheat the oven to 180°C (approximately 350°F).
5 Divide the dough into 8 equal portions and roll out each slightly larger than the tartlet pans. Use to line the buttered pans, trimming edges. Prick the pastry base with a fork several times, cover with parchment paper and dried beans and bake for 10-15 minutes.
6 Remove the tartlets from the oven. Remove the dried beans and the parchment paper.
7 Fill the tartlets with the vanilla cream.
8 For the rhubarb: Rinse the rhubarb, peel, cut into small cubes, sauté with the sugar in a pan for 1-2 minutes, pour off the liquid, drain and distribute 3/4 between the tartlets.
9 For the meringue: Whip the egg whites until foamy. Continue whipping, gradually adding the powdered sugar, until glossy and mixture stands in firm peaks.
10 Cover the tartlets with 2/3 of the meringue, top with the majority of the remaining rhubarb, the remaining meringue and then the remaining rhubarb pieces.
11 Increase the oven to 200°C (approximately 400°F) and bake for about 10 minutes, until golden brown. Remove from the oven, let cool and serve.