Boil potatoes until soft. Add tbsp. butter and 1/2 - 3/4 cups milk and mash. Mix in Tex Mex cheese.
While potatoes are boiling, add some oil to a large frying pan. Cook the beef, onions, garlic, mushrooms and spices for 5 minutes or until done. Drain.
Sprinkle with flour and gravy mix and mix well.
Add the beef stock and mix well.
Add the tomato paste, Worcestershire sauce and corn and mix well.
Simmer for 5 - 8 minutes.
Spread in a large casserole dish, sprayed with Pam.
Top with mashed potatoes sprinkled with extra cheese if desired.
Bake 20-30 min. at 350 F.