Place the onion in the bottom of the slow cooker to rest the chicken on.Rinse the whole chicken and pat dry with a paper towel.
In a small bowl, mix together the butter, herbs, crushed garlic, sea salt, and black pepper.
Place the chicken in the slow cooker, then fully coat the chicken with the herb butter.Place the lid on the slow cooker and cook on low for 6-8 hours or high for 4-6 hours until a thermometer reads 165℉.
Once cooked, let the chicken cool for 5-10 minutes before carving. Serve with a drizzle of the herb butter drippings over the chicken.
optional
After the chicken has fully cooked, move the chicken to a sheet pan and broil on high for roughly 5-8 minutes until the skin is golden and crispy.