Preheat the oven to 400°F. Grease a 12-cup muffin pan.
Popover batter is easiest made in a blender. Add all the ingredients to the blender and blend until smooth.
Pour the batter into the prepared pan, filling each cup about 2/3 full.
Bake for 25 minutes, then reduce the oven heat to 350°F and bake for an additional 15 minutes, until the popovers are deep brown.
Remove from the oven, prick the side of each popover with a sharp knife to let the steam out, and let popovers rest for 5 minutes to finish setting. Remove from the pan, and serve immediately. Or, to keep them crisp longer, allow them to sit in the turned-off oven for 10 to 15 minutes before serving.