Spray a large crock pot with vegetable oil. Add the cream soup, onion soup mix, beef broth, garlic powder, onion powder, parsley, salt and pepper together; whisking until smooth. Fold in the mushrooms.
Place the venison roast into the crock pot and spoon some of the mixture over the roast. Cover and cook on high for 5 hours (8 hours on low). If the roast is frozen, cook on high for 8 to 10 hours; or until meat falls apart.
If you don't have a slow cooker, you can bake the roast at 275 degrees for 4 to 5 hours until tender.