Use a 6-quart slow cooker. Place the cored peppers upright in the insert. In a large mixing bowl, whisk together the eggs, cheese, mushrooms, green onions, salt, and pepper.

Spoon this egg mixture evenly into the peppers and place the pepper tops back on. Pour the water into the bottom of the insert around the bases of the peppers.

Cover and cook on low for 6-7 hours, or on high for 3 hours. Your breakfast peppers are finished when the egg is set and the peppers have begun to wilt.