These buttery gems puff up and become golden brown in the oven.
Heat oven to 425 degrees. Whisk together the milk, flour, and salt until just incorporated. The mixture will be lumpy.
Beat in eggs and egg yolks, one at a time, until just incorporated. Be careful not to overmix. The batter should still be lumpy.
Brush inside of popover tins with a generous amount of butter. Divide batter evenly among buttered tins. Bake 20 minutes.
Reduce oven temperature to 350 degrees; bake until puffed and golden brown, 15 to 20 minutes more. Remove tins from oven, and turn out popovers; serve immediately.
Popover tins usually make six popovers; youâ€™ll need two for this recipe. The batter can be made several hours ahead and chilled.