Heat the oven and grease a 9×13-inch baking dish.
Melt the butter in a skillet, add the beef and cook until browned.
Season the beef and add the flour.
Add the vegetables and broth. Then, add milk and remove from the heat.
Transfer the beef mixture to the prepared baking dish and smooth into an even layer. Top with the tater tots.
Bake for 40 to 45 minutes until the tots are browned and the filling is bubbly
Cool the casserole for 15 minutes before topping with scallions or parsley and serving.