Preheat oven to 350°F (175°C). Spray a 9×13-inch baking dish with cooking spray.

In a large bowl, whisk together eggs, sour cream, milk, salt, pepper, and shredded cheese until just combined.

Heat a large skillet over medium heat. Add beef sausage and cook until fully browned, breaking it into small pieces. Drain excess fat.

Add cooked sausage to the egg mixture.

In the same skillet, sauté bell peppers and green onions for 2–3 minutes until slightly softened.

Add vegetables to the egg mixture and stir to combine.

Pour mixture into prepared baking dish.

Bake for 35–50 minutes, until edges are set and the center is just slightly jiggly.

Remove from oven, let rest 5–10 minutes, then slice and serve.