In a slow cooker, combine the peanut butter, coconut milk, soy sauce, honey, rice vinegar, garlic, ginger, red pepper flakes, salt, and black pepper. Stir until well combined.
Add the chicken thighs to the slow cooker, making sure they are well coated with the sauce.
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 using two forks and stir it back into the sauce.
Serve the peanut chicken over rice or noodles, garnished with chopped green onions and crushed peanuts.