Combined the softened butter, salt and sugar. Add the flour and stir just to combine. Then add the egg yolks and milk without overworking the dough. Place in the refrigerator.
Combine the milk and cream. Combine some of the cold liquids with the cornstarch and flour and stir with a whisk. Thin with the remaining cold liquids and add the vanilla scraped from the bean pods. Bring to the boil slowly and add the sugar when cooked.
Roll out the pastry to a thickness of 2 mm and press into the buttered rings. Refrigerate for at least 1 hour. Fill with clay pie weights and blind bake in a 170°C convection oven for approximately 20 minutes.
Prepare the flan mixture and pour into the blind baked pastry shells. Refrigerate for at least 4 hours. Bake in a 200°C convection oven for approximately 20 minutes.