To scald milk, pour the cold milk into a heavy-bottomed saucepan, set the pan over medium heat, stir the milk frequently with a wood or heat-proof spatula. Stir until milk reaches 180 degrees for 15 seconds or there is a film of foamy cream forming, then remove from heat.
When scalding milk, it is important to not let the milk boil over. This can be avoided by keeping a close eye on the milk, using a pan that is taller than needed, keeping the heat on medium, and removing the milk from the heat when it shows signs of boiling. If the milk begins to form a foamy cream on the surface, if tiny bubbles have formed at the sides of the pan, or there are wisps of steam coming from the milk, the milk is scalded and should be removed from the heat to prevent boiling.
It is also possible for the milk to scorch, which can be avoided by keeping a close eye on your milk, stirring frequently and checking if your spatula has picked up any solid milk residue from the bottom of the pan. If it has, turn the heat down slightly. Scorching can also occur if the milk begins to scald for too long.