Why Do Donuts Have Holes? Here’s the “Hole” Story

The answer – both possible explanations, that is – is much more practical than you might expect. Donuts start their short lives out as mounds of dough that are separated, manipulated, and then fried in hot oil. The problem with cooking a patty of dough is that it’s hard to cook evenly. By the time you get the middle cooked all the way through, the edges are too crispy.

Source: https://www.distractify.com/p/why-do-donuts-have-holes