When your timer goes off, grab a
spatula and stir ever so gently to mix the melted chocolate into the custard base. If you stir like crazy, the temperature will drop too quickly, and you’ll end up with grainy chocolate. (Mexican chocolate is traditionally coarse ground and can be crumbly in texture, but I prefer my pots de crème to be sinfully smooth.) Steady, slow stirring is essential for ensuring a stable emulsion.