Preheat oven to 400° F. Generously oil two Muffin Makers. Place on two 1⁄4 Sheet Pans.
Cube butter. In a large microwaveable bowl, heat milk and butter on high for 1 min. Remove from the microwave, whisk until butter melts.
Whisk in eggs until foamy; add mix. Whisk vigorously until no lumps remain.
Stir in cheese.
Divide evenly between muffin wells. Add toppings, if desired.
Bake 12 min, or until golden brown and a toothpick inserted in the center of the muffins comes out clean. Rest in pan 10 min or until cool enough to unmold.