Pumpkin pie is one of the archetypal holiday dishes, almost as important as the turkey itself. Every dedicated baker has strong ideas on how it's best made and will argue eloquently for hours about the selection of ingredients or the correct baking technique. One frequent source of controversy is the dairy ingredient, most often evaporated milk or half-and-half.
About Pumpkin Pie
Pumpkin pie consists of a rich, well-spiced custard baked in a pastry shell. The main ingredient is pumpkin puree, either from a can or made at home by cooking and pureeing a suitable fresh pumpkin. The filling is normally sweetened with brown sugar, though honey and maple syrup are also used occasionally. It's liberally flavored with warm spices including cinnamon, cloves, ginger and nutmeg or mace and given the correct custard texture by the addition of eggs and some form of milk. Although whole milk or heavy cream can be used, most recipes call for evaporated milk or half-and-half.
The Role of Milk or Cream
Most custards are made with some form of milk or cream, which help create the dessert's characteristically soft texture. During the mixing process, the proteins from the custard's eggs are dispersed evenly through the milk. When the mixture is heated, the egg proteins try to congeal and solidify, as they would in a frying pan. Instead, because they are spread thinly throughout the milk, the proteins make a sort of three-dimensional sponge that immobilizes the moisture. The end result is a soft and smoothly thickened texture, rather than the firmness of cooked eggs.
Evaporated Milk vs. Half-and-Half
Although individual bakers often hold strong preferences, either evaporated milk or half-and-half can make an excellent pumpkin pie. The primary difference between them is nutritional. According to the U.S. Department of Agriculture's nutritional database half-and-half is higher in fat, with just under 28 g per cup as opposed to evaporated milk's 19 g per cup. On the other hand, evaporated milk is higher in carbohydrates, at 25.3 g per cup as opposed to 10.4 g in the half-and-half. Evaporated milk is slightly higher in calories but also significantly higher in nutrients including calcium, iron, potassium, phosphorous and magnesium.
For many home bakers, the choice of a dairy ingredient in their pie is as simple as using whatever Mom's recipe calls for. If you're blessed with a more inquiring turn of mind, you might want to bake four or five pies, each with a different milk ingredient, and see which one you like best. There will be slight differences in the recipes, reflecting the different makeup of each dairy ingredient. In the context of a holiday meal, the differences in nutrition and fat content are probably unimportant, but if you love pumpkin pie it's worth picking a favorite.