Los Angeles — FAT (Fresh. Authentic. Tasty.) Brands Inc., parent company of Fatburger, Buffalo’s Express and 13 other restaurant concepts, is heading to Illinois with a newly inked deal in partnership with A.D.T.J. Development LLC to open 25 Fatburger and Buffalo’s Express stores throughout the state of Illinois — in particular, in Chicago and the surrounding area. The locations are slated to open over the next 8 years. Both the Fatburger and Buffalo’s Express brands have been populating the West Coast, East Coast and regions in the South. This will …