1. Heat a large skillet over medium-high heat.
2. Add ground beef and finely diced onions to the skillet.
3. Cook the beef, breaking it up with a wooden spoon, until browned and the onions are translucent (about 5-7 minutes).
4. Drain excess fat if desired, leaving a small amount for flavor.
5. Add minced garlic and cook for an additional 30 seconds until fragrant.
6. Stir in Worcestershire sauce, salt, and pepper to season the meat mixture.
7. In a medium bowl, combine mayonnaise, ketchup, sweet pickle relish, white vinegar, paprika, onion powder, and garlic powder to make the homemade Big Mac sauce.
8. Whisk the sauce ingredients together until smooth and adjust seasonings to taste.
9. Reduce the heat of the cooked beef mixture to low.
10. Add about half of the prepared Big Mac sauce to the skillet with the meat mixture and stir well to combine.
11. Allow the meat and sauce to simmer for 2-3 minutes to meld the flavors.
12. Lightly toast sesame seed buns for added texture and warmth.
13. Place a slice of American cheese on the bottom half of each bun.
14. Spoon a generous portion of the meat mixture over the cheese layer.
15. Add shredded lettuce and dill pickle chips on top of the meat.
16. Spread additional Big Mac sauce on the top bun.
17. Place the top bun onto the sandwich stack.
18. Serve your Big Mac Sloppy Joes immediately and enjoy.