This makes a dozen standard-sized muffins. If you want to use large muffin tins, it will only make six, and you’ll have to bake them for 48 minutes.
3 T plus 1/2 C butter, melted
1/3 C Parmesan cheese, finely grated
1/2 C white Cheddar cheese, grated
8 eggs, room temperature
2-2/3 C 2% or whole milk, room temperature
3 large green onions, finely chopped
2-2/3 C flour
1-1/2 t salt
Preheat oven to 375 F. Brush 12 nonstick muffin cups with 3 T melted butter and sprinkle with the parmesan cheese.
In a large bowl, beat the eggs, then add the milk, the green onion, and the remaining 1/2 C butter. In a smaller bowl, blend the flour, salt, and Cheddar. Gradually whisk the dry ingredients into the wet.
Divide the batter into the muffin cups. Bake without opening the oven (this is important!) until puffed and crusty brown. If you have an oven window, you can watch, but it should take 38 minutes.