Sift flour and milk powder into a mixing bowl. Stir in sugar and salt. Cut butter into flour with a pastry cutter until mixture resembles fine breadcrumbs. Add beaten egg and vanilla essence and mix to a firm dough. Wrap the pastry in a plastic bag and chill for 30 minutes.
Roll out pastry between two sheets of plastic wrap. Line small tartlet cases with the pastry. Prick the base and chill for 20-25 minutes. Bake in preheated oven at 180°C for 20-25 minutes.
To make the filling: Heat the milk and cream together with the vanilla essence. Once the mixture is warm, remove from the heat (cover to prevent a skin forming). Beat the egg and egg yolk with the sugar until pale and fluffy. Sift in the flour.
Bring the milk and cream to just below boiling point. Pour into the egg mixture and stir vigorously, then strain the mixture into a non-stick pan. Bring to a boil stirring constantly (to prevent the base from being burnt). Simmer for 1-2 minutes until the mixture thickens. Remove and leave to cool completely.