Use a 4-quart slow cooker. Place the chicken in the bottom of your slow cooker insert. In a mixing bowl, combine the diced onion, marmalade, mustard, soy sauce, ginger, and red chili flakes. Stir well. Pour this sauce evenly over the top of the chicken. Stir to evenly disperse the sauce.

Cover and cook on low for 6-8 hours or on high for about 4 hours. Serve over white or brown basmati rice if desired.