Preheat your oven to 450°F. Grease six 6-ounce custard cups or popover pans with butter and set aside.
Place the eggs into a medium bowl and beat until light and fluffy. Add in the flour, milk, vanilla and salt, then mix until just smooth. Don't overmix!
Place the popover pans into the oven and heat for 2 minutes.
Once heated, remove from the oven and carefully fill each cup half full of batter. Return to the oven.
Bake for 20 minutes then WITHOUT OPENING the door, decrease the oven temperature to 350°F and bake for 10- 20 minutes more until the batter "pops over" the edge and is a darker goldewn brown.
Whisk together the sugar and cinnamon in a medium bowl. Toss each popover in the sugar mixture, coating well and serve warm.
Notes
to make these savory to go with a roast, leave out the vanilla and serve plain