Heat oven to 350 degrees.
Grease a 12 muffin pan with butter. Set aside.
Finely chop the peppers and mushrooms. Mix together in a bowl. Set aside.
Whisk eggs together in a bowl. Set aside.
Add 2 teaspoons of the vegetable mix into each muffin hole.
Fill each hole halfway with the egg mixture.
Season each with freshly cracked salt & pepper.
Cook at 350 degrees for 15 - 17 minutes.