Step 1

Preheat oven to 325 degrees F (165 degrees C). Prepare a 13x9-inch baking dish with cooking spray.

Step 2

Beat eggs, milk, sour cream, and salt together in a large bowl with wire whisk until well blended. Mix ham, bell peppers, mushrooms, and green onion into the egg mixture; pour into the prepared baking dish.

Step 3

Bake in the preheated oven until a knife inserted into the center comes out clean, about 50 minutes. Cover top of dish with Cheddar cheese; continue baking until cheese is melted, about 3 minutes.