As in this recipe, I've found that the loftiest, fluffiest popovers are the result of a batter prepared in the blender. This significantly helps to aerate the eggs and combine the ingredients into a smooth batter. If a blender is not an option, popover batters can be mixed via hand with a whisk or by using a stand mixer. Just make sure that you are whisking or mixing the batter until it is frothy.