Light whipping cream by John Spottiswood.

Unlike heavy cream or whipping cream, lower-fat substitutes like half-and-half and evaporated milk tend to "break" or curdle when added to sauces. To prevent this from happening, heat the sauce over low or medium heat, or reduce the cream substitute before adding it to the sauce. Don't let the sauce boil. Cream sauces made with lower-fat cream substitutes also tend to have less body; to correct for that, consider adding 1 tablespoon flour or 2 teaspoons cornstarch to the sauce for every cup of evaporated milk substituted. Stir the thickener into a paste first to prevent lumps.