Prep the chicken: Season chicken breasts with salt and pepper on both sides.
Cook the chicken: Heat olive oil or butter in a large skillet over medium heat. Add chicken and cook 5–6 minutes per side until golden brown and fully cooked. Remove from skillet and set aside.
Cook aromatics: In the same skillet, sauté onion and garlic until soft and fragrant, about 2–3 minutes.
Add walnuts and sauce: Stir in chopped walnuts, chicken broth, soy sauce, and honey. Cook for 3–4 minutes until the sauce thickens slightly.
Combine and simmer: Return the chicken to the skillet, coating it with the walnut sauce. Simmer for 2–3 minutes so the flavors meld.
Serve: Plate the chicken, spoon over extra sauce and walnuts, and garnish with parsley or green onions if desired.