Pre-heat oven to 450, or higher if your oven does not run hot. Coat cups of a popover pan with melted butter or oil, and flour lightly. The sticky sides help the popovers pop!
Sift salt and flour into a small bowl. Whisk eggs, milk and butter together in a larger bowl. Slowly add flour mixture to egg mixture and blend until flour chunks are the size of peas or smaller.
Pour batter into the pan. Don't fill cups above 3/4 full. If your pan has small cups, recipe may yield 8 or more popovers.
Bake popovers at 450 for 15 minutes. WITHOUT opening the oven, turn down to 350 for another 20 minutes or longer for crisper popovers. DO NOT OPEN THE OVEN TO CHECK THEM! If tops aren't yet browning, the cold air will cause the popovers to fall.
Serve hot with butter and jam. Popovers can be kept hot in the oven for another 30 minutes. Enjoy!