Preheat your oven to 350 degrees.In a large Dutch oven preheated to medium-high heat add the olive oil, ground beef, green pepper, onion, garlic, salt and pepper. Cook the vegetables and meat until no longer pink about five minutes. Make sure to drain off any fat.Next, stir in the corn, water, tomato paste, relish, and mustard. Bring to a soft boil and then reduce heat to a simmer. Simmer for a few minutes uncovered.Stir in a 1/2 cup of the cheddar cheese. Remove the Dutch oven from the heat and top with cheeseburger mixture with mashed potatoes. Top the mashed potatoes with the remaining 1/2 cup cheddar cheese.Place the Dutch oven in the oven (uncovered) for about 20 minutes or until heated through. Garnish with fresh parsley!