Brown the beef and onion: In a large skillet over medium-high heat, cook the ground beef and diced onion until the beef is browned and no longer pink. Break up the meat with a wooden spoon as it cooks to ensure even browning. Once fully cooked, drain off any excess grease from the pan to prevent the mixture from becoming too oily.
Create the sloppy joe sauce: Add the tomato sauce, ketchup, mustard, Worcestershire sauce, brown sugar, onion powder, and garlic powder to the skillet with the beef. Stir thoroughly to combine all ingredients, coating the beef evenly with the sauce. Let the mixture simmer for about 3-5 minutes to allow the flavors to meld together and the sauce to thicken slightly.
Preheat the oven: Preheat your oven to 400°F (200°C) to ensure it reaches the proper temperature for crisping the garlic toast while melting the cheese.
Arrange the toast: Arrange the frozen garlic toast slices on a large baking sheet in a single layer, making sure they don't overlap. This will ensure they cook evenly and maintain their crispness.
Assemble the sloppy joes: Spoon a generous amount (about 2-3 tablespoons) of the sloppy Joe mixture onto each piece of garlic toast, spreading it evenly but leaving a small border around the edges. Sprinkle an equal amount of shredded cheddar cheese over the top of each loaded toast.
Bake until golden: Bake for 10 to 15 minutes, or until the toast is hot and crispy on the bottom, and the cheese is fully melted and bubbly with slightly golden edges.
Serve hot: Carefully remove from the oven and transfer to plates. Serve immediately while hot and the cheese is still gooey for the best flavor and texture experience.