In a large skillet over medium heat, brown the ground beef until fully cooked, breaking it apart with a wooden spoon as it cooks. Drain any excess grease.
Add the diced onion to the skillet and cook for another 3-5 minutes until the onion is softened.
Stir in the ketchup, mustard, brown sugar, Worcestershire sauce, garlic powder, onion powder, salt, and pepper. Mix well and let simmer on low heat for about 10 minutes, allowing the flavors to meld.
While the mixture is simmering, prepare the burger buns by toasting them lightly (optional).
Once the sloppy joe mixture is ready, spoon generous amounts onto the bottom half of each toasted burger bun.
Top each sloppy joe with shredded cheddar cheese, shredded lettuce, diced tomatoes, and sliced pickles.
Spread a spoonful of the Special Sauce on the top half of the bun and place it on top of the assembled sloppy joe.
Serve immediately with your favorite sides.