Prep. time: 45 minutes
Cooking time: 20-25 minutes at 180°C / 350°F
Rising time: 1 hour 45 minutes

The little extra: instead of granulated sugar, you could use coarsely crushed pieces of cane sugar. 

Dough

1. Prepare the dough: heat the milk to lukewarm. Crumble the yeast into the milk. In a bowl, combine the flour, salt and sugar.
2. Form a well in the centre of the dry ingredients and add in the egg and milk.
3. Mix the dough, first briskly with a wooden spoon, and then by kneading it thoroughly by hand, incorporating the softened butter, until it is smooth and no longer sticks to the sides of the bowl (add a little more flour if necessary).
4. Form the dough into a ball, cover with a towel and leave to rise for an hour in a warm place.
5. Once the dough is risen, roll it out into a disc the diameter of a large pie. Place on a buttered baking sheet and leave to rise again for 45 minutes.

Pastry cream

1. Halve the vanilla bean lengthwise and scrape out the black seeds.
2. Place the seeds and bean into a saucepan with the milk and bring to a simmer.
3. In a bowl, beat the egg, yolks and sugar until light and pale. Mix in the sifted flour and potato starch, and then incorporate the hot milk while stirring constantly.
4. Pour the mixture into a saucepan and, still stirring constantly, let thicken over very low heat.
5. Remove from the heat and remove the vanilla bean. Dot the surface with the butter and let cool to lukewarm. 

Cooking

1. Preheat the oven to 180 °C / 350 °F.
2. Beat the egg for the glaze with the icing sugar and milk. Brush it over the surface of the dough, then sprinkle with the granulated sugar. Bake in the middle of the oven for 20-25 minutes.
3. Remove from the oven and let cool.

Finishing

1. In a bowl, whip the chilled cream. When it is firm and forms peaks, gently fold it into the pastry cream.
2. Cut the baked pastry circle into half widthwise and place the bottom half on a serving platter. Sprinkle with rum, cover with all the cream, then cover with the top half without pressing down.
3. Refrigerate until just before serving. The tart should be eaten within 24 hours.