Preheat the oven to 350 degrees F and spray a 9x13-inch pan with cooking spray.

In a large bowl, combine the eggs, sour cream, milk, shredded cheese, salt, and pepper, then mix on low speed with electric mixers until just combined.

Heat a large skillet over medium heat, add the pork sausage, and cook until browned, breaking it into small pieces; drain most of the grease and add the sausage to the egg mixture.

Add the diced bell peppers and green onions to the same skillet and sauté for 2-3 minutes, then add them to the egg and sausage mixture and stir everything to combine.

Pour the complete mixture into the greased 9x13-inch pan and bake for 35-50 minutes, or until the edges are set and the center is just barely jiggly.

Store any leftover casserole in the fridge for 3-4 days and reheat in the microwave for enjoyment.