Helena, Mont. — Slim Chickens, a leading fast-casual franchise which features dine-in and drive-thru in the “better chicken” segment, is expanding into Montana. Mike Sartwell, who is an existing multi-unit franchisee with Slim Chickens, is bringing four new restaurants to Montana. The first location, which is a conversion, will be located at 1450 Prospect Ave. in Helena. Sartwell has an extensive portfolio of restaurants across North Dakota, Montana, Missouri and Illinois. His portfolio consists of quick-service and fast-casual brands. “Our group has developed Slim Chickens restaurants in North Dakota, and …