Season chicken liberally with black pepper and place in a crock pot.
Combine honey, garlic, soy sauce, ketchup and red pepper flakes in a medium-sized bowl and whisk until all ingredients are thoroughly incorporated. Add green onions and stir (reserving some for garnish if desired).
Pour honey mixture over chicken pieces then cook, covered, on high for 3-4 hours (or low for 5-6 hours) or until chicken is cooked through and tender.
Remove chicken from crock pot then cover to keep moist. Increase temperature of crock pot to high (if not already on high) and replace lid.
Add cornstarch to a small bowl or cup then slowly add water; stir until smooth. Add cornstarch slurry to crock pot, cover and heat until sauce thickens (about 30 minutes).
Chop chicken thighs into bite-sized pieces and add back to crock pot. Gently stir to coat chicken with sauce. Reduce heat to “warm” until ready to serve.
Serve chicken and sauce over white rice. Garnish with chopped green onions if desired.