Preheat oven to 400 degrees. Lightly coat 8 popover cups, muffin cups, or custard cups with cooking spray.
In a food processor or blender, combine eggs, flour, and salt. Process until well blended, 10 seconds.
With the machine running, pour in milk through the feed tube. Process until smooth. Stir in chives.
Fill prepared cups with batter, filling to 1/4 inch below the rim. If using individual cups, set them well apart on a baking sheet.
Bake 35 minutes, until puffed and golden brown. (Don't open oven door while popovers are baking or they will fall.) Remove from oven and run a sharp thin bladed knife around the edge of each popover to loosen. Invert into a basket and serve immediately.