Lightly grease the inside of the slow cooker/crock pot with cooking spray; set aside.
In a large mixing bowl combine eggs, milk, parmesan, salt, black pepper, Italian Seasoning, garlic powder and chili powder; using a whisk, beat the egg mixture until thoroughly combined.
Add broccoli florets, diced peppers, chopped onions, and garlic to the insert of your slow cooker; stir in the prepared egg-mixture.
Cover and cook on HIGH for 2 hours. Start checking at 1 hour 30 minutes for doneness. Omelette is done when eggs are set. You can also cook it on LOW for 3 to 3.5 hours.
Sprinkle with cheese and cover; let stand 2 to 3 minutes or until cheese is melted.
Turn off the slow cooker.
Optional: Garnish with chopped peppers, tomatoes, chopped onions and fresh parsley.
Cut the omelette into 8 pieces and serve.