Preheat the oven to 450 degrees F. Grease a nonstick, standard 12 muffin tin and place in the oven to heat while you prepare the batter.
In a large bowl, sift together the flour and salt. In a smaller bowl, whisk together the eggs, milk, and melted butter until blended. Pour the wet ingredients into the dry and use a whisk to mix them together. Fill each hole in the muffin tin between 2/3 and 3/4 full. Bake for 10 to 12 minutes and then reduce the oven temperature to 350 degrees F. Bake until they develop a nice brown color, an additional 15 minutes; they should feel crusty. Opening the oven door while popovers bake increases the chances they will deflate so look through the window but don't give in to temptation!
Remove the tin from the oven and turn the popovers out onto a flat surface to cool. Pierce the sides with the tip of a small knife to allow steam to escape as they cool. Serve immediately.
Recipe copyright, Alex Guarnaschelli