If you've never had popovers, you've never really eaten breakfast. Actually popovers are good for dinner or lunch, too. If you're a grown-up there's no reason not to eat insanely naughty stuff whenever you want! If anyone complains at you, tell 'em I said it was OK!
Popver cups or pan - I use the silicone tall popover pan that I purchased on amazon.com a few years ago. (see what one looks like)
Set your oven to 425 degrees F. While it's warming, mix the batter and get the cups ready.
Melt the butter; I usually put it in a small bowl and pop it into the microwave for 10-20 seconds. Drip a couple drops (seriously, just a couple drops!) into each of the compartments of your popover tray and spread it around with a fingertip. You should have most of your butter, or at least half, left when you are done with this step.
Put the milk and eggs in a bowl. Add the melted butter and salt. Give everthing a preliminary whisking to combine it all, then add the flour. Beat the batter vigorously, and try to loft as much air into it as you can while doing so. The batter should be pretty runny. Beat it for about a minute so it starts to form large air bubbles on the surface when you stop beating it. It's crucial to get the air into the batter because she's what's going to make it rise!
Pour the batter into the cups and put them into the oven. In 20 minutes, reduce the heat to 325 degrees. Keep cooking them until they are foamed up and large and golden on the top. When you start to smell them, it's time to collect your guests around the table because popovers are good for about 3 minutes after you take them out of the oven and will rapidly collapse into rubbery hockey puck-like things. If you want to make them smell extra insanely good while cooking (but this will have no effect on their flavor) add 2 drops of vanilla extract to the batter before you mix it.
Serve with butter or nutella or jam. Be careful - they are full of hot steam!