Courtesy of The 2001 Old Farmer's Almanac article, “The Pie Ladies of Plain City, Ohio.”
Louella fills the pie shell only about half full, then moves the pie to the oven rack and adds the rest of the filling using a cup. She prefers Pyrex pie pans to metal.
Separate one of the eggs, whip the white until stiff, and set aside. Beat the yolk and the remaining 3 eggs. Add sugar, salt, flour, and vanilla, and stir well. Add the scalded milk. Stir in the egg beaten white. Pour into pie shell. Sprinkle with cinnamon. Bake at 425°F for 10 minutes, then at 350°F for about 20 minutes, or until set.