Preheat the oven to 425º F. Brush the cups of a popover pan with melted butter and place in the oven while it preheats.
In a large bowl, whisk the flour and salt to combine. In a large liquid measuring cup, whisk the milk and eggs to combine. Add the milk mixture to the flour while whisking constantly until a smooth, very liquidy batter forms.
Gradually whisk in the melted butter, mixing just until fully incorporated. Transfer the batter to a large liquid measuring cup (or other spouted vessel).
Remove the hot pan from the oven, and pour the batter into the cavities of the pan. Fill each cavity just over halfway full.
Bake the popovers—without opening or adjusting the oven—until they are golden brown and very tall, 20 to 25 minutes.
When you remove the popovers from the oven, puncture each on the top and/or the side with a sharp paring knife to release some of the steam inside. Serve the popovers warm, immediately.
Leftover popovers should be stored in an airtight container for 1 to 2 days, and re-warmed in the oven for the best effect.
I always carry three kinds of hot sauce in my purse. I have a soft spot for making people their favorite dessert, especially if it's pie. My first cookbook, The Fearless Baker, is out on October 24, 2017.