Preheat your oven to 400°F (200°C). Arrange the hash brown patties in a single layer in a 9x13 inch baking dish. Bake for about 25 minutes until golden brown and crispy.

While the hash browns are baking, prepare the special sauce by mixing grated onion, mayonnaise, salt, sweet pickle relish, white vinegar, sugar, mustard, paprika, and onion powder in a bowl until fully combined.

Heat a skillet over medium-high heat and add olive oil. Add the ground beef, cooking until browned (about 7-10 minutes). Season with black pepper and Worcestershire sauce. Stir in the chopped onion and cook until soft.

In a large mixing bowl, combine the cooked beef mixture with 2/3 cup of special sauce and 1 1/3 cups of shredded cheese, stirring until well mixed.

Once the hash browns are crispy, flip them with the crispy side up. Spoon the beef and cheese mixture over the hash browns. Sprinkle remaining cheese on top and optionally add sesame seeds. Bake for an additional 10-12 minutes until cheese is melted and bubbling.

After baking, let the casserole rest for about 5 minutes. Prepare fresh iceberg lettuce and remaining special sauce. Top each portion with lettuce and chopped dill pickles before serving.