Put the ground venison in a bowl, with an egg, mustard, Worcestershire sauce and 4 tablespoons of beef broth. Mix thoroughly. Add breadcrumbs as well as salt and spices. Should form a meatloaf texture that can be formed into patties, may need more breadcrumbs to get to this texture if it is too wet and doesn't stay together.
In your skillet add 1 tbsp of butter, fry the onion and mushrooms for 5-7 minutes to brown over low medium heat until slightly tender. Add flour and fry for 3-4 minutes, stirring occasionally, over medium heat to create a roux.
Pour in the beef broth, stir, bring to a boil. Break all the lumps of flour. Shape the meat into patties (about 4 for every pound is good) and fry them in another pan in the remaining butter, about 5 minutes per side, to brown the outsides.
Pour sauce with mushrooms and broth into the meat pan, (or transfer meat patties into mushroom gravy pan. Cover with a lid and cook on low heat for another 20 minutes. Serve together.