Pastry cream

1. In a bowl, using an electric whisk, beat the eggs with the cornstarch, vanilla extract, and 125 ml milk (taken from the 1 litre).
2. Pour the remaining milk into a saucepan with the vanilla sugar, sugar, and vanilla powder.
3. Bring to a boil.
4. Pour the boiling vanilla milk over the egg mixture while whisking (electric whisk).
5. Pour everything back into the saucepan and cook over very low heat, stirring constantly with a wooden spatula.
6. Let it gently bubble for a few seconds only; the mixture should thicken slightly.
7. Transfer the pastry cream to a clean bowl and cover directly on the surface with cling film to prevent a skin.
8. Let it cool completely before using.

Assemble the flan

1. While the pastry cream cools, roll out the puff pastry to about 5 mm thick.
2. Line a tart tin about 22–24 cm wide and about 4 cm deep.
3. Refrigerate.
4. Once the pastry cream is fully cooled, preheat the oven.
5. Heat the oven to 180°C, bottom heat. If your oven runs hot, reduce to 170°C before baking for more even cooking of the puff pastry.
6. Whisk the pastry cream to loosen it.
7. Remove the chilled pastry case and prick the base with a fork.
8. Pour in the pastry cream and smooth the surface.
9. Bake on the second shelf from the bottom for 30–40 minutes.
10. Make sure the puff pastry base is fully baked; then you can switch to fan/convection to colour the top nicely.
11. When the flan is fully baked and nicely coloured, remove from the oven and cool on a wire rack before unmoulding.
12. Let it cool completely before serving.