Cut the vanilla pod lengthwise and scrape out the pulp. Bring the milk with the pulp and pod to the boil in a small saucepan and let it simmer at low heat for about 5 minutes. Whip 2 egg yolks with sugar in a bowl until light creamy, stir in starch. Remove the pod from the vanilla milk. Pour hot milk into the egg yolk mixture while stirring. Pour it back into the pot and let it boil down for about 3 minutes at medium heat while stirring constantly. Pour cream into a bowl, place foil directly on the cream and let it cool down for about 1 hour.
Take 12 apricot halves out of the tin and let them drain. Use the remaining apricots for other purposes. Defrost frozen dough plates side by side on a piece of baking paper for about 10 minutes, roll out to 10 x 20 cm and cut in half crosswise. Place on a baking tray lined with baking paper. Stir vanilla cream until smooth and spread evenly on the puff pastry squares. Leave a rim of about 0.5 cm all around.
Whisk 1 egg yolk with 2 tablespoons of water. Place one apricot half in each of 2 opposite corners of the dough squares, fold over free corners and brush with egg yolk mixture. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 20 minutes. Remove and let cool on a cake rack.