To cook a
serving of food well done is to
brown,
crisp, or
burn the food in an attempt to
enhance the
flavor. Two of the most common usages of well done food is
meat and
pizza.
A well done steak will be brown inside and either brown or black on the outside. The flavor of it is a lot drier then normal meat. The meat tends to turn flavorless.
For pizza it is considered well done, when the pizza's top starts to harden into blackened crust and the bottom of the pizza starts to darken. Thicker pizzas tend to be ruined in the process of making a well done pizza. Thin pizzas with light sauce will tend to have a better flavor when well done, especially as the sauce burns off.