Preheat the oven to 425 degrees F. Preheat for at least 20 minutes, if possible.

Generously grease muffin tins with softened butter. Make sure they are well coated and run a bit right around the top of the pan around each muffin cup. Place the pans in the oven for exactly 2 minutes to preheat.

Meanwhile, whisk together the flour, salt, eggs, milk, and melted butter until smooth. Pour into a container with a spout; it just fits in a 2 cup Pyrex measuring cup. The batter will be thin.

Working quickly, fill the muffin pans 3/4 full and bake for about 20 to 22 minutes. Try not to peek. Watch closely at the end as oven times can vary wildly – they should be golden, not deep brown.

When you remove popovers from the oven, quickly pierce each one with the point of a sharp knife to let out excess steam and immediately after, turn out so they don’t lose the crispness on the exterior. You should have a slightly crispy, tender, browned exterior and a moist, beautiful lacey interior.