Place all ingredients in a saucepan over medium heat. The chicken may not be totally covered by liquid (once butter melts) which is fine.
Once butter is melted, adjust heat so the liquid is simmering. Cook for 50 minutes, turning once, or until chicken can be easily shredded. The sauce should be thickened but if it's too watery, then remove the chicken and simmer until it reduces.
Shred chicken with 2 forks (I do this in the saucepan). Serve!