Step 1

Preheat the oven to 450° with the racks positioned in the highest and lowest positions. Pour the milk into a microwave-safe bowl or measuring cup. Microwave in 20-second intervals until warm (about 40 seconds total). Add the warm milk to the container of a blender.

Step 2

Add the eggs to blender with the milk; pulse until combined and frothy. Add the flour, melted butter, salt and pepper; pulse until combined. Add chives, if using; pulse until combined. (Batter will be very thin.)

Step 3

Spray wells and tops of a 12-cup regular muffin tin or popover pan with nonstick cooking spray. Place a small bit of butter in the bottom of each cup (about 1/8 teaspoon per cup).

Step 4

Place the greased pan in the oven for 5 minutes. Carefully remove the pan from the oven. Working quickly, pour the batter evenly into muffin tin wells, filling each about three-quarters full. Place the pans on bottom rack of the oven and bake for 20 minutes. Without opening the oven, reduce the temperature to 350° and bake for 15 minutes more. (Turn the oven off and let the popovers cool for ten minutes in oven for sturdier puffs, if desired.)

Step 5

Remove the popovers from oven and serve immediately. Sprinkle with the additional chives, if desired.