To a blender, add the melted butter, eggs, and milk. Pulse until completely blended.
Add the dry ingredients, and pulse to combine. Let the popover batter rest for 15 minutes.
Once the oven has been preheated, carefully drizzle the butter into the bottom of each cup, while working quickly.
Bake for 20 minutes, then reduce the heat to 350 degrees without opening the oven door. Bake for 10 more minutes.
Remove the fluffy popovers from the hot oven and serve with butter or jam.