Cook the sausage substitute for 4 minutes in the microwave on the high setting. Add to this the refried beans and the breadcrumbs together. Add to this the croutons and the sliced and shredded cheese. Add water to the mixture. Next add the mayonnaise and tomato sauce to the mixture. Next add the pepper, salt, and garlic powder. Mix well. Finally add the gravy to the top of the loaf. Cook for 10 to 15 minutes in the microwave, high setting.