First melt the butter and allow it to cool for a few minutes.
In a large mixing bowl (if you have one with a spout, that really works great here), whisk together the flour, salt, eggs, milk, and butter until just combined and nearly no lumps remain. Whisk in half of the chopped herbs.
Preheat your oven to 450°F with the popover pan inside. Once the oven is ready, remove the hot pan and spray with a little nonstick cooking spray. Fill each cup 2/3 full with the very liquid-y batter.
Sprinkle on the remaining herbs. Bake for 15 minutes, then turn the oven heat down to 300°F and continue to bake for another 8-10 minutes until the edges of the popovers begin to turn golden brown and start to pull away from the pan.