Grease a 9 x 9-inch or an 11 x 7-inch square baking dish.
For potato topping; combine half a can of cheddar cheese soup with hot mashed potatoes; set aside.
In a fry pan brown ground beef with oregano, chopped onion and garlic; drain off fat, then stir in Worcestershire sauce, mushrooms, shredded cheddar cheese and Parmesan cheese.
Meanwhile cook mixed veggies according to package directions; drain well then add to beef mixture along with the remaining half of cheese soup.
Add in your choice of additions, then season with salt and pepper to taste; mix to combine and simmer uncovered for about 20-30 minutes over medium-low heat stirring occasionally.
Spoon meat mixture into greased pan; spread the hot mashed potato mixture evenly over top.
Bake for 25-30 minutes or until topping is light golden brown.
Sprinkle 1/3 cup shredded cheddar cheese on top then allow to melt.
ADDITIONS, use one or all of 3/4 cups good quality beef broth mix/wisked with 2 tablespoons flour (for a thicker ground beef mixture) - one can cream style corn/ one tablespoon Dijon mustard - 1/3 cup Heinz chili sauce or ketchup - 1/2 package of dry onion soup mix - 2 tbsp Kitchen Bouquet browning sauce OR 1-2 small packages beef bouillon powder.