Preheat the oven to 400 degrees. Divide 1 tbsp of melted butter in each cup of a popover pan. Place the pan into the oven and allow it to heat through.
Whisk room temperature eggs until light and frothy.
Continue to whisk as you add the flour.
Add the milk while whisking, and then whisk in the remaining ingredients.
Carefully remove the popover pan from the oven.
Divide the batter between the popover cups.
Bake for 30-35 minutes until the tops are puffed, golden, and brown. Do not remove them from the oven until then as they will deflate.