Heat the oven to 350°F
Crumble and brown the sausage and drain fat. Don’t cook the sausage. Browning it will release some of the fat and help maintain the frittata’s texture. Set aside to cool while you chop the onions and peppers.
Whisk the eggs and then add the sausage, onion, bell pepper, salt, black pepper, and one cup of cheddar cheese.
Use the olive oil to coat a 10″ x 10″ baking pan or cast iron skillet. Pour the mixture into the oiled pan and top with the second cup of cheese.
Bake at 350°F for 20 to 25 minutes. Cool ten minutes before cutting.