Milk Reduction

As anyone who has ever boiled milk has learned, milk traps steam as it is heated, and if the heating continues past a certain point, a small explosion occurs in the pan. The milk suddenly ‘foams up’, as the cookbooks say, and overflows the pan. In order to overcome this problem when reducing milk over high heat, one should start off with a sufficiently large pan so that even foaming will not overflow the sides. After a while, when the milk has reduced and thickened, it becomes necessary to lower the heat very far and to keep stirring, both to prevent scorching and to stir back any skin forming on the surface of the milk.