Confectioner's custard (Crème pâtissière, or French pastry cream) (Slideshow version)
Stage 8/11 :
Cooking is complete when custard is of a good consistency, in other words like a thickish purée, but not too firm..The custard thickens quite quickly, especially if the heat is high, so do not to hesitate to take pan off heat, while continuing to stir, if this happens.
Also, remember that your custard will continue cooking for a little while after being removed from the heat, so bear this in mind when deciding at what point to stop...