Preheat the oven to 350 degrees. Spray meatloaf or baking dish with cooking spray. Mix the chickpeas, onion, garlic, red and green pepper and mushrooms in a food processor until chopped. Work in batches if necessary. Transfer the vegetables to a large bowl. Add the egg, Parmesan cheese, salt and pepper. Mix until completely combined and form into a loaf. Place in the baking dish and cook for 40-45 minutes. Meanwhile, combine the ketchup, Dijon mustard and vegetable broth (or water) in a small bowl. Remove the meatloaf from the oven and brush the ketchup mixture onto the loaf. Bake for an additional 10 minutes. Allow the vegetarian loaf to sit for about 10 minutes before slicing and serving. Enjoy!