1/2 - 1 teaspoon each of dried thyme and dried rosemary (adjust to your taste)
Pat chicken thighs dry with paper towel and trim off excess fat. Combine the onion powder, garlic powder, herbs, salt and pepper. Coat the chicken evenly with the combined seasoning.
Heat 1 tablespoon of oil a large pan over medium-high heat and sear chicken thighs in batches until browned on each side and no longer pink in centre (about 8 minutes each side, depending on thickness). Add remaining oil if needed for second batch. Transfer to a plate; set aside and keep warm.
To the same pan, melt the butter and add the mushrooms. Season with salt and pepper and cook until soft (about 3 minutes). Add the garlic, parsley, thyme and rosemary; sauté until fragrant (about 1 minute).
Return chicken to the pan and cook till chicken is cooked thru. Season with salt and pepper to your taste. Garnish with fresh spring onion (optional). Serve immediately.