McDonald’s is gearing up to introduce a brand-new addition to its US menu next week: the Chicken Big Mac. With hopes of bringing in more customers and expanding its already impressive chicken offerings, the fast-food giant is betting that this latest twist on its iconic sandwich could help it reverse a challenging year. The Chicken Big Mac is essentially a variation of the original Big Mac, but with two tempura-battered chicken patties in place of the usual beef. This sandwich, which has already made waves in international markets, will be available to US customers starting on October 10 as pa…