Custard balance demands strict adherence to proportions. The sweet spot for classic diner-style French toast is one large egg for every 1/4 cup (60 ml) of dairy. If you shift past this threshold by adding too much milk, the bread stays waterlogged and never sets properly in the center. If you use too many eggs, you end up tasting a breakfast omelet wrapped around toast.
For a batch serving two people (four thick slices), whisk 2 large eggs with 1/2 cup of whole milk or half-and-half. Whisk the mixture vigorously in a wide, shallow dish until the egg whites fully blend into the milk without visible strings. Add 1 teaspoon of pure vanilla extract, 1/2 teaspoon of ground cinnamon, and a pinch of fine kosher salt. Salt cuts through the richness of the egg yolks and brings out the floral notes of the vanilla.
Cinnamon presents a minor challenge because it is hydrophobic; ground spice tends to float in clumps on top of the liquid. To blend it smoothly, whisk the cinnamon into the eggs first before pouring in the dairy. The natural fats in the egg yolks disperse the spice evenly across the custard base.
