The ultimate pouring custard

Put the vanilla bean paste in a pan with the whole milk and double cream. Heat until bubbles just start to appear on the surface, then take off the hob. In a large bowl, whisk together the egg yolks and caster sugar. Slowly pour the milk mixture over the egg mixture, whisking constantly. Pour into a clean pan and set over a medium heat. Stir constantly until the mixture just starts to thicken and coats the back of a spoon (7-10 minutes). Take off the heat and pour into a warm jug. Serve straight away.