Everybody Needs a Little Fat

• Without fat from milk, French toast doesn't have the satisfying "mouthfeel" that makes it taste so good. Mouthfeel provides texture that is both emotionally and physically important in food's appeal -- think of the satisfying crunch of potato chips and the smoothness of ice cream. Your French toast is most appealing when you add a dab of heavy cream to the milk, but even low-fat milk contains some fat, about 2 grams in 1 cup.

The Science of French Toast

• Milk provides the base for the rich custard that makes ice cream, pudding and French toast taste so good. When you gently blend the eggs and milk for French toast, you are actually creating an emulsion, keeping the two substances suspended into one whole rather than separating. Water, with its lack of any fat molecules, doesn't bind or emulsify as well with the eggs, leaving the inside of the French toast somewhat soggy and the outside coated with cooked egg.

A Mixed Blessing

• Whisking the soaking liquid in just the right way helps make your French toast light and fluffy. The milk and eggs must be thoroughly mixed to form a completely combined and smooth custard, with no bits of egg left separate. Unfortunately, no amount of mixing will hold water and eggs together; they will eventually separate while the bread soaks or when you put the bread in the pan.

Getting the Most From Milk

• The best custard mixture for French toast has neither too much milk nor too little; use about 1 cup of milk per 4 eggs. As long as it contains some fat, any type of milk works, such as soy milk or coconut milk. Use bread that is somewhat stale so it soaks up even more milk, and leave the bread in the custard mixture long enough time for it to completely soak through, about a minute on each side.