Preheat the oven to 375°F. Grease a 9x13 inch baking dish.
In a large skillet over medium-high heat, cook the ground beef, onions, and bell pepper until beef is browned and vegetables are tender, 5-7 minutes. Drain excess fat.
Add the garlic and cook for 1 minute until fragrant.
Stir in the ketchup, mustard, brown sugar, Worcestershire sauce, chili powder, salt, pepper and beef broth. If the mixture seems dry, add a splash more beef broth to loosen it up.
Spread half of the tater tots in an even layer in the prepared baking dish.
Top with the sloppy joe meat mixture and spread in an even layer.
Sprinkle half the shredded cheddar cheese over the meat.
Top with the remaining tater tots and remaining cheese in an even layer.
Bake for 30-35 minutes or until the casserole is bubbly and the tater tots are a crispy golden brown.
Let stand for 5 minutes before serving.
Garnish with chopped green onions.