Creme:
Bring the milk to the boil together with the split vanilla pod. Let infuse for about 10-15 min then remove the vanilla pod. Whisk egg yolks, sugar and corn flour until light and fluffy. Combine the milk and egg mix until smooth, return to the heat and let come to the boil under constant whisking. Add butter and remove the pan from the heat and whisk until smooth. Pass through a sieve and chill as soon as possible.
Dough:
Sieve the flour onto your worksurface, add the butter, powdered sugar and salt. Pinch together quickly to a crumbly mixture. Add the egg yolks and form to a dough. Let the dough rest for at least one hour in the fridge.
Assembly:
Heat the oven to 190 C. Roll half the dough out to about a 3 mm thickness. Cut to fit your chosen moulds. Press gently into the moulds, leaving a tiny bit of overlap over the edges. Fill to 3/4 with the cooled creme. Roll the rest of the dough and cut to form lids for the moulds. Gently seal the lids over the moulds. Stab each pastry to make a hole for hot air to escape during baking. Bake for about 25 min until nicely golden. Remove from moulds and dust with powdered sugar when cool.