In a bowl, mix together all the Big Mac sauce ingredients and set aside.
In another bowl, season the ground chicken with paprika, garlic powder, onion powder, salt, and pepper. Spread an even layer of the seasoned chicken onto one side of each flour tortilla.
Heat a lightly oiled griddle over medium heat. Place the tortillas meat-side down and cook for about 3 minutes until the chicken is browned. Flip the tortillas and top each with a slice of American cheese. Cook for another 1–2 minutes, until the cheese is melted and the chicken is fully cooked.
Transfer the tacos to a taco rack. Top each with shredded lettuce, chopped pickles, chopped onion, a generous drizzle of Big Mac sauce, and a sprinkle of sesame seeds.