Preheat oven to 350 F. Cut up seitan, mushrooms, and broccoli into bite-sized chunks. In medium saucepan add yeast flakes, milk, and salt and pepper. Heat until yeast is dissolved. Add seitan and veggies to mixture and cook until soft. Add vegan cheese until all veggies are coated. I used vegan sliced vegan cheese such as Tofutti and I think it works just as well as any others. Remove from heat. Cut into bread top to make a lid about 3 inches wide and very shallow (like a pumpkin), set aside. Hollow out the loaf and season inside with nutritional yeast. Fill with mixture and replace lid. Wrap in foil and bake for 30 mins. Let cool and slice into 3 inch wide slices and serve.