Preheat your oven to 350 °F (175 °C). Spray a 9 × 13‑inch pan with cooking spray.

In a large bowl, combine the eggs, sour cream, milk, shredded cheddar cheese, salt, and pepper. Use an electric mixer on low speed until just combined.

In a large skillet over medium heat, add the pork sausage and cook until browned, breaking it into small pieces with a wooden spoon. Drain most of the grease, then transfer the cooked sausage into the bowl with the egg mixture.

In the same skillet, add the diced green bell pepper, red bell pepper, and sliced green onions and sauté for 2‑3 minutes until slightly softened. Add the sautéed vegetables into the egg-sausage mixture and stir everything together until evenly combined.

Pour the mixture into the greased 9 × 13‑inch pan. Bake for 35 to 50 minutes, until the sides are firm and the center has just a slight jiggle—it will continue to firm up as it cools out of the oven.

Take it out of the oven and allow it to sit for a few minutes before cutting into portions and serving.