You'll love this Italian Sausage and Egg Casserole featuring bell peppers, red onion, Fontina and Parmesan! It's low-carb, gluten-free and keto-friendly.
Lightly grease a 9x13 pan with cooking spray. Preheat your oven to 375 degrees F.
Rinse and dry the peppers and cut the stems out. Cut each pepper in half, then in half again. Remove the seeds and membranes. Then slice the peppers and chop them into pieces about ½ inch long. Set them aside.
Peel and chop the onion (start with 1 medium one) and measure out 1 cup of chopped onion.
Shred the Fontina on a box grater (or you can partially freeze the cheese and then throw it in your blender to grate it).
Place the crumbled sausage in a 12-inch skillet and break it up with a wooden or plastic spoon. (If you are starting with sausage links instead of crumbled sausage, cut the links in half and use a small, sharp knife to remove the casings. It will be easier to break the meat up with your hands than trying to do it with a spoon.)
Turn the heat on medium high to brown the sausage. Stir the sausage often until it is no longer pink. Using a slotted spoon, transfer the cooked sausage to your baking pan.
In the same skillet, and keeping the small amount of sausage fat that there, add a tablespoon of olive oil and heat it on medium high. Add the onions and peppers and give them a stir. Lightly sprinkle on the salt, moving from the top to the bottom of the pan in rows. Sprinkle on the black pepper and garlic powder, again covering all of the veggies.
Sauté the peppers and onions, stirring often, for 5-6 minutes, or until they are tender. Transfer the veggies to a colander in the sink to drain. Use paper towels to carefully pat them and absorb excess liquid. Then transfer the drained peppers and onions to your baking pan and stir them into the sausage.
Stir the Fontina and 1 cup of Parmesan into the sausage and peppers.
In a medium bowl, whisk the eggs well. Then, whisk in the milk. Pour the egg mixture over the sausage and peppers. Sprinkle on 2 tablespoons of Parmesan. Bake, uncovered for 40 minutes, or until the top is set and browned a bit, and a cake tester or toothpick inserted in the center comes out clean.
Let the casserole rest for five minutes before cutting into it and serving. Store leftovers in the fridge, covered with foil (not plastic, because that will create too much moisture). Use within four days.
Notes
If you don't see ground Italian sausage in the meat department, try asking your grocer's butcher for it. Otherwise, you'll have to buy the links and remove the casing to crumble the meat.
You can assemble this up to 24 hours in advance before baking it. Store the unbaked breakfast casserole covered in the refrigerator, then bake as directed.