1. Place a 6-cup popover pan in bottom third of oven. Place baking sheet on rack underneath to catch any drips. Preheat oven to 400°F.
2. In a small saucepan over medium-high heat, warm milk until small bubbles form around the edges. Put flour and salt in a fine-mesh sieve; sift onto sheet of waxed paper. In a large bowl, whisk eggs until frothy, about 2 minutes. Slowly whisk into hot milk. Gradually whisk in flour mixture until almost smooth.
3. Remove pan from oven; spray cups with butter-flavored non-stick vegetable spray (chemical free, if possible). Fill cups three-quarters full. Bake 15 minutes; Rotate pan 180 degrees. Continue baking until popovers are browned and puffed, 30 minutes more; do not open oven after rotating pan.
4. Meanwhile, 10 minutes before the popovers are to be done, melt the butter and set it aside. Mix the cinnamon and sugar in a shallow bowl. When you remove the popovers from the oven, let them rest just a moment until they’re cool enough to handle. Remove one from the pan (without puncturing it in any way) and thoroughly brush it all over with the melted butter, then dredge it in the sugar and cinnamon mixture to coat completely. Repeat with each. Enjoy immensely.
NOTE: These can be made into a savory treat by eliminating the butter, sugar and spice and substituting 3 ounces of grated Gruyere cheese sprinkled on top of the batter just before it’s popped into the oven. Heavenly.