Preheat the oven to 400 and spray a large casserole with cooking spray.
Put the beef and a pinch of salt and pepper to a large skillet and cook until browned, breaking it up with a wooden spoon or a spatula. Stir in the Worcestershire sauce and set aside.
Put the carrots, celery and onion into a food processor and process until finely chopped.
Melt the butter in a medium pot and add the chopped veggies. Sauté for 3-5 minutes until they are starting to get soft.
Stir in a pinch each of salt and pepper, followed by the flour. Pour in the milk and simmer until nice and thick. Stir in the cheese until melted.
Add the beef to the vegetable cheese sauce and stir. Transfer to the casserole.
Lay the Tater Tots on top of everything, doing your best to get them in a single layer.
Bake until everything is bubbling and golden, about 40 minutes. Let it cool for 5 minutes, then scoop into warmed bowls, garnish with parsley (optional!) and serve!
Notes
Ground Beef: We like the 80/20 variety of ground beef, but you can use a lower fat version…or ground lamb, turkey or even chicken.
Tater Tots: These are chopped potatoes that are seasoned and pressed into little cubes. Look for them near the French fries in the frozen food aisle.