1/2 cup chopped onion
1/2 cup chopped green bell pepper, or to taste (I also add the same amount of red bell pepper
1/2 teaspoon salt
1/4 teaspoon ground black pepper
1/4 teaspoon garlic powder
1/2 cup shredded Cheddar cheese
Grease 12 muffin cups well. (They stick to paper liners.)
Heat a large skillet over medium-high heat and stir in sausage; cook and stir until sausage is crumbly, evenly browned, and no longer pink, 10 to 15 minutes; drain.
Beat eggs in a large bowl.
Stir in onion, green pepper, salt, pepper, and garlic powder.
Mix in sausage and Cheddar cheese.
Fill muffin cups just a little over 1/2 full. They deflate some after cooling, but when cooking they rise way up like a souffle, so if overfilled, they might run over.
Bake in preheated oven until a knife inserted near the center comes out clean, 20 to 25 minutes. (Again, ovens very, so check yours before the time is up.)
As a side note, for me, these make more than 12. You might halve or quarter the recipe the first time to see how it goes.
DH prefers his with the sausage, but I like mine with turkey bacon, seems like it adds a little more flavor. DH doesn't like any type of bacon anyway.