Start by heating a skillet over medium heat. Add the breakfast sausage, breaking it apart with a spatula as it cooks. Sauté it until it’s browned and fully cooked, typically about 5-7 minutes. Once done, drain any excess fat and set aside to cool slightly.
In a large mixing bowl, crack the 9 eggs and whisk them until they are well beaten. Pour in the milk and add the salt, whisking everything together until smooth and combined.
In the same bowl, add the cooked sausage, cubed Italian bread, and both types of cheese. Gently fold everything together until the bread is fully coated in the egg mixture and the ingredients are evenly distributed.
Preheat your oven to 350°F (175°C). Grease your 9x13 inch baking dish with a little oil or cooking spray. Pour the mixture into the prepared dish, spreading it out evenly with your spatula.
Once your oven is preheated, place the baking dish in the oven and bake for 30-35 minutes, or until the eggs are set and the top is golden brown. You can check for doneness by inserting a knife in the center; it should come out clean.
Once baked, remove the casserole from the oven and let it cool for about 5-10 minutes. This will help it set a bit more and make it easier to cut into squares. Serve warm.
