The orange winter squash that gives pumpkin pie its main filling is pumpkin.
Pumpkin pie is made from cooked and puréed pumpkin blended into a sweet custard, usually with eggs, sugar, milk or evaporated milk, and warming spices. Cinnamon, ginger, nutmeg, and cloves or allspice create the flavor commonly associated with the dessert. The filling is baked in a single pastry shell, typically without a top crust.
Pumpkins are native to North America, and the fruit became part of the culinary exchange between the Americas and Europe. Early pumpkin “pies” were not always modern desserts: colonists sometimes cooked pumpkin with savory ingredients or baked food inside a whole pumpkin. A recognizable sweet custard version appeared in the 1796 cookbook American Cookery.
A common misconception is that canned pumpkin must come from the large carving pumpkins used for jack-o’-lanterns. Pie pumpkins are generally smaller and less stringy, while commercial purée may use varieties of Cucurbita moschata. Related winter squashes, including butternut squash, can substitute, but the canonical ingredient and answer remains pumpkin.