Place the chicken thighs in the slow cooker.
In a medium bowl, whisk together the peanut butter, coconut milk, soy sauce, honey, rice vinegar, garlic, ginger, and red pepper flakes until smooth.
Pour the peanut sauce over the chicken in the slow cooker, ensuring the chicken is well coated.
Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the chicken is tender and cooked through.
Once cooked, shred the chicken in the slow cooker using two forks and stir to combine with the sauce.
Serve the peanut chicken over cooked rice or quinoa, and garnish with chopped green onions and peanuts.