Make this simple, scrumptious Popovers with just 5 ingredients and your favorite popover pan or muffin pan. Popovers use steam instead of traditional leavening agents to rise and puff over the top over the pan.
Adjust an oven rack to the middle position (do not preheat oven). Brush the inside of a standard 6-cup popover pan with 1 tablespoon melted butter.
In a deep bowl or large measuring cup, whisk together remaining 1 tablespoon melted butter, eggs, and milk. Stir in the flour and salt until just combined. Divide the batter among the popover pan cups, filling each cup about ⅔ full (you can eyeball it, but if you're a stickler, each cup gets about 1/3 cup + 1 tablespoon batter).
Place the popover pan in a cold oven and immediately preheat to 375 degrees. Bake until the popovers are tall, deep golden brown, and puffy, about 35 to 45 minutes. During the first 30 minutes, keep the oven door closed at all times. Do not peek.
Remove them from the oven and immediately make a small slit in the side of each popover with a paring knife so steam may escape. Cool 5 minutes in pan.