The parmesan here is the catalyst that makes the cheesy flavors jump out of the airy centers. These popovers are best when baked at the last minute, but you can make the batter ahead.
Yield: Makes 24 popovers
Active Time: 10 min
Total Time: 1 3/4 hr (includes chilling)
1 cup whole milk
2 large eggs
1 cup all-purpose flour
2 tablespoons unsalted butter, melted, divided
1/2 teaspoon salt
1/8 teaspoon black pepper
1/3 cup finely chopped provolone
2 tablespoons grated parmesan
1 1/2 tablespoons chopped chives
Equipment: a 24-cup mini-muffin pan
Whisk together milk, eggs, flour, 1 tablespoon butter, salt, and pepper until smooth, then stir in cheeses and chives. Chill 1 hour to allow batter to rest.
Preheat oven to 425°F with rack in upper third.
Butter muffin pan with remaining tablespoon butter, then heat in oven until butter sizzles, about 2 minutes.
Gently stir batter, then divide among muffin cups (they will be about two-thirds full). Bake until puffed and golden-brown, 18 to 20 minutes. Serve immediately.
Cooks' note:
Batter can be made 1 day ahead and chilled.