3 tablespoons melted butter, cooled so that it is warm not hot
Preheat oven to 450F. Position rack on the lower half of your oven so that your popovers have room to rise. Place the un-greased popover pan in the oven to warm.
Combine the eggs, milk and salt. In a food processor or blender, combine the eggs, milk and salt. Process for a few seconds until just combined. You should not see streaks of yolk.
Add the flour and pulse until combined, about 20 seconds. Scrape down sides of your blender or food processor bowl to get any flour off the sides. There should not be any big lumps in the batter.
Add the melted butter and pulse until combined, about 20 seconds. The batter should be slightly frothy on top, as shown in the photo above.
Grease heated popover pan. Carefully remove heated popover pan from oven and spray well with PAM or other cooking spray.
Pour the batter into the popover molds. Fill each mold about 3/4 high.
Bake. Place pan on lower rack in oven and bake for 20 minutes. Do not open the oven door.
Reduce heat to 350F and bake for another 15 minutes. Do not open the oven door for first 10 minutes. After 10 min you can check periodically for doneness. Popovers are done when they are a deep golden brown.