Preheat the Oven: Preheat your oven to 375°F (190°C). This temperature will ensure your casserole cooks evenly, with the tater tots getting crispy on top while the filling stays moist and flavorful underneath.
Brown the Meat: To a 12-inch, oven-safe skillet over medium heat, add the ground beef and onions. Cook, stirring occasionally and breaking up the meat as you go, for about 8-10 minutes, or until the meat is no longer pink. Drain excess grease if necessary. This step builds the flavor foundation for your casserole.
Create the Sauce: Add the ketchup, chicken broth, brown sugar, mustard, salt, pepper, and garlic powder to the skillet. Stir until all ingredients are combined. This mixture creates that classic sweet and tangy Sloppy Joe flavor that makes this dish so comforting.
Add the First Layer of Cheese: Turn off the heat. Sprinkle 1 cup of cheddar evenly over the mixture. This middle layer of cheese helps bind the meat mixture to the tater tots and adds rich flavor.
Top with Tater Tots: Arrange the frozen tater tots in a single layer on top of the cheese. Depending on the size of your skillet, you may not use the entire package of tater tots. A single layer ensures each tot gets crispy during baking.
Bake the Casserole: Transfer the skillet to the oven and bake for 30-35 minutes, or until the filling is bubbly and the tater tots are golden brown and crispy. This initial bake cooks the tots and allows the flavors to meld together.
Add Final Cheese Layer: Top with the remaining cheese. Bake for an additional 5-10 minutes, or until the cheese is melted and slightly golden. This final layer of cheese brings everything together.
Garnish and Serve: Garnish with chopped parsley for a pop of color and freshness. Serve hot, allowing the casserole to cool slightly before digging in.