Preheat oven to 350°F and grease a 9x9 or 9x13-inch baking dish with baking spray. Set aside.

In a skillet over medium heat, cook the ground meat, seasoning with salt and pepper, and break it into crumbles. Once cooked, transfer to a large mixing bowl.

Add tomato purée, drained corn, and drained green beans to the bowl with the meat. Stir well to combine and set aside.

In another bowl, mix the instant potato flakes with boiling water, sour cream, and butter. Stir until smooth and season with salt and pepper to taste.

Spread the meat and vegetable mixture evenly into the prepared baking dish.

Spoon the mashed potatoes over the meat layer and spread to cover completely.

Cover with foil and bake for 30 minutes until the casserole is bubbling at the sides. Remove foil, sprinkle cheese on top, and return to oven for 10 more minutes, or until cheese is melted.

Remove from oven and serve hot.