Preheat the oven to 425°.
Add the popover pan or muffin tin to a sheet tray and preheat in the oven for 10 minutes.
In a large bowl whisk together the eggs, butter, and milk until combined and smooth.
Next in a separate large bowl whisk together the flour and salt until combined and then add in the wet ingredients.
Whisk until completely smooth and set aside. If you cannot get it completely smooth, add it to a blender and blend on high for 30 seconds.
Take the preheated pan out of the oven and immediately spray with non-stick spray.
Evenly pour in the batter until each cup is about ⅔ to ¾ of the way full.
Bake at 425° for 20 minutes and then at 325° for 10 minutes.
