Preheat the oven to 350F.
Lightly spray a 9x13 casserole dish with cooking spray. Set aside.
In a large stock pot, boil the potatoes until they are fork-tender. Drain and set aside.
5 small potatoes
Cook the diced onions and brown the ground beef in a large skillet over medium-high heat. Drain the excess grease and set aside.
2 lbs lean ground beef, 1 small onion
Season the ground beef mixture.
2 tablespoons Worcestershire sauce, 1 teaspoon garlic powder, kosher salt and black pepper
In a large bowl, whisk together the cream soup, milk, salt, and pepper.
2 cans of cream soup, or 4 cups homemade Cream Soup Substitute, 1½ cups milk
Into the prepared baking dish, add half of the cooked ground beef mixture, then half the cooked potatoes. Add half of the cheese on top of the potatoes. Repeat with the remaining ingredients.
1½ cups of shredded cheese
Cook at 350F for 30 minutes until the cheese is melted and the casserole is bubbly.