Preheat oven to 350°F (175°C) and grease a 9×13-inch baking dish.
- In a skillet over medium heat, cook sausage until browned. Drain excess grease.
- Add diced onion and bell pepper (if using) to the skillet and sauté until softened. Remove from heat.
- In a large bowl, whisk together eggs, milk, salt, and pepper.
- Spread cubed cornbread evenly in the prepared baking dish.
- Top with sausage and vegetable mixture.
- Pour egg mixture evenly over the top.
- Sprinkle shredded cheddar cheese over everything.
- Bake uncovered for 35–40 minutes, or until eggs are set and cheese is golden and bubbly.
- Remove from oven, let cool slightly, and garnish with green onions or parsley before serving.