Preheat oven to 450F (230C) and lightly grease a 12-count popover pan or two 12 count muffin tin with cooking spray. Set aside.
Place eggs in a large bowl and, using an electric mixer, beat on low speed until eggs are frothy and pale yellow (you can do this by hand if you don't have an electric mixer but it will take longer).
With mixer on low, add milk and melted butter and beat until well-combined.
Sprinkle salt over batter and stir.
Add flour, stirring on low-speed until batter is completely combined. Batter will be very thin and almost watery.
Evenly divide batter into prepared tin (it's very thin, so I like to use an ice cream scoop to pour the batter, helps keep things less messy), filling each about ⅔-¾ of the way full and transfer to 450F (230C) oven**.
Bake on 450F (230C) for 20 minutes, then, without opening the oven door, reduce the heat to 325F (160C) and bake an additional 15 minutes.
Remove from oven and serve immediately -- these taste great topped with butter!
*If you use a popover pan you will get 12 popovers, if you use a muffin tin you will get at least 18**Important Note! Place a cookie sheet lined with parchment paper or foil beneath your popover pan or muffin tin. The butter tends to spill over the sides as the batter bakes and will drip onto your oven, causing a lot of smoke and a messy oven. Avoid this and set yourself up for easy cleanup by placing a pan underneath.