2. Grease a 9x13 inch casserole dish with butter or oil.
3. In a large skillet over medium heat, cook ground sausage until browned and crumbly.
4. Add onions to the skillet and cook for another minute until they become translucent.
5. Crack 8 large eggs into the skillet and stir gently to scramble them.
6. Pour the egg mixture into the prepared casserole dish.
7. Sprinkle shredded cheese over the top of the eggs (if using).
8. Bake in the preheated oven for 20-25 minutes or until the eggs are fully cooked and the cheese is melted on top.
9. Season with salt and pepper to taste before serving.
Enjoy your delicious egg sausage casserole main dish! This recipe is a great way to make breakfast or dinner for a large group of people. It's also easy to customize by adding veggies like bell peppers, mushrooms, or spinach.