Here’s how to make popovers:

1. Preheat the oven. As mentioned, it takes a hot oven to create the necessary steam. Preheat the oven to 425 degrees.
2. Mix the batter. With a whisk or whisk attachment, beat the eggs, milk, and salt together. Change to the paddle attachment and mix in the flour until completely smooth. Continue mixing for several minutes to develop the gluten. If the recipe calls for melted butter, add that after the gluten is developed so that the fat will not interfere with the gluten development.
3. Prepare the pan. Use a pastry brush to grease the insides of the popover cups. If you are using a muffin pan, grease every other cup. Place 1/2 to one teaspoon of butter in the bottom of each cup.
4. Bake the popovers. Remove the pan from the oven and fill the cups half full. Bake at high heat for twenty minutes; the popovers should pop during this baking. Reduce the heat to 350 degrees and continue baking for 15 minutes for large popovers. During this period, the popovers should dry and become rigid. (Different ovens cool differently and may require different times.)
5. Release the steam. Turn off the oven, open the oven door, and quickly make a one-inch slit in the side of each popover to release the steam. Close the oven door and let them sit for ten or fifteen minutes. During this period, the interior of the popovers should become dry and sturdy.
6. Cooling the popovers. Lift the popovers from the pan immediately after removing the pan from the oven by grasping the tops with an oven mitt. Let them cool slightly before serving.

Leftover popovers can be reheated in the oven for five minutes at 325 degrees to make them crisp again.