First lightly coat the cups of a muffing tin with oil or baking spray, then add about a teaspoon of melted butter to each cup.
Beat together the eggs, milk, 1 tablespoon of butter, sugar, and salt. Add flour and beat to combine until you have a smooth batter. (I used my trusty immersion blender for this)
Remove the pan from the oven (with care!! hot butter!!) and fill each cup about halfway. I might go as far as ⅔ next time, to see if I get more loft, but the halfway mark produced very satisfying results.
Bake for about 15 minutes at 425, then turn the oven down to 350 F and bake for another 15 minutes. Bittman says that it is very important that you not open the oven until at least the 30 minute mark, presumably so you don't cause popover collapse, and I would do what he says.
Remove from oven and remove popovers immediately from the pan. I used a twisting motion to loosen the ones that were a tiny bit reluctant to leave the pan.
These are at their best when served hot, but I enjoyed leftovers for a couple of days by splitting them and reviving them in my toaster.
Recipe by The Bright Kitchen at https://www.thebrightkitchen.com/brown-butter-popovers/