Big Mac Casserole

Name: Big Mac Casserole
Ingredients: 8 frozen hash brown patties; 1 onion; 1 cup mayonnaise; 2 teaspoons Kosher salt, divided; 2 tablespoon sweet pickle relish; 2 teaspoons white vinegar; 2 teaspoons sugar; 2 teaspoons mustard; 1 1/2 teaspoons paprika; 1 teaspoon onion powder; 1 tablespoon olive oil; 1.25 lb. ground sirloin; 1 teaspoon freshly ground black pepper; 2 teaspoon Worcestershire; 8 ounces block Cheddar cheese, grated, divided; 2 teaspoons sesame seeds; 3 cups shredded iceberg lettuce; ½ cup hamburger dill pickle slices, roughlychopped