
Preheat the oven to 450 degrees F.
In a large bowl, whisk the eggs until smooth. Add the milk and salt, then continue whisking for a couple more minutes.
Gradually add the flour to the egg mixture and mix until smooth without any lumps.
Gently fold in the cheddar cheese and green onions, and then set the mixture aside to rest for at least 10 minutes.
Meanwhile, position the popover pan in a baking tray and place it on the lower rack of the oven as it preheats.
Once preheating is complete, apply cooking spray to the popover pan and carefully pour the prepared batter into each slot, filling them almost to the top.
Return the baking tray to the oven and bake for 20 minutes at 450 degrees F. After that, reduce the oven temperature to 350 degrees F and continue baking for an additional 12-15 minutes, or until the tops are golden brown.
Once baked, take the baking tray out of the oven and gently pierce the tops of the popovers with a butter knife to release steam. Allow the popovers to cool for at least 5 minutes.
Slice the popovers and serve them with butter to enjoy.