First prepare the mashed potatoes, by peeling and chopping the potatoes.
Dump chopped potatoes into a large pot of boiling water and cook until potatoes are tender, about 20 minutes. Drain water from potatoes.
Add butter, salt, and milk to potatoes and mix well with a handheld mixer till smooth.
For the casserole, cook ground beef in a skillet, seasoned with 1/2 teaspoon pepper, 1/2 teaspoon garlic powder and 1/2 teaspoon oregano. Crumble the meat and cook until it is no longer pink. Grate the cheese.
Preheat oven to 350 degrees.
In a 2 quart dish, layer ground beef across the bottom. Sprinkle with season salt.
Drain and rinse corn and green beans. Then layer the corn, sprinkle again with season salt.
Next, layer green beans, sprinkle with season salt.
Next, layer mashed potatoes and sprinkle with cheese and season salt.
Cover dish and bake at 350 for about 20-25 minutes, or until everything is heated through. Allow to cool for 5 minutes then cut into 6-8 slices.
Serve with cantaloupe slices. (Serving size: 1 slice, 1/4 cup cantaloupe)