Preheat the oven to 375 F. Spray a 2 ½-quart baking dish with cooking spray; set aside.
In a large skillet set over medium-high heat, brown the ground beef and onion together. Drain any excess fat.
Season with garlic powder, parsley, salt, and pepper, then stir in the Worcestershire sauce. Stir in the soup and sour cream until well combined, then remove the skillet from the heat.
Transfer the mixture to the prepared baking dish, spreading it into an even layer. Layer on the green beans, season with salt and pepper to taste, then sprinkle on 1 cup of the cheese.
Spread the tater tots evenly over the top, then sprinkle on the remaining cheese.
Bake for 35-45 minutes, until tater tots are golden brown and cheese is melted. Serve immediately.
This nutrition information is based on the exact products I used in this recipe. Brands and sizes of products could alter exact nutrition and should always be calculated independently.