Slow Cooker Chicken and Dumplings

2 boneless, skinless chicken breasts
1 small white onion, finely chopped
1 tbsp butter
1 can cream of chicken soup
2 cups chicken broth
1/2 tsp pepper
1 package Pillsbury Grands biscuits

Place the chicken breasts, onion, butter, soup, and broth in the bowl of a slow cooker.
Cover and cook on high for 4 hours, then remove the chicken and shred with two forks. Return the chicken to the slow cooker.
Cut the biscuits into 8-piece wedges, then place in the cooker add the pepper, cover, and cook for an additional 2 hours.