Scald the milk and the pistachio paste in a heavy-based saucepan. Whisk together the egg yolks and castor sugar in a bowl and beat until pale and double in volume and the sugar has dissolved. Beat the flour into the egg mix. Pour the scalded milk onto the egg mix and whisk until fully incorporated. Pour into a clean saucepan and return to a low heat. Continuously stir with a wooden spoon until thick. Transfer the pistachio crème pâtissière into a clean bowl and dust with icing sugar to prevent a skin from forming on the surface. Cover the pistachio crème pâtissière with clingfilm when cool and refrigerate until ready to use.
© 2005 Liam Tomlin. All rights reserved.