Dry chicken thighs with paper towel and place in a large bowl. Combine the onion powder, garlic powder, herbs, salt and pepper. Coat the chicken evenly with the combined seasoning and a drizzle of olive oil.Heat a large pan or skillet over medium-high heat and sear chicken thighs in batches until browned on each side and almost cooked through. Remove chicken from pan and set aside.To the same pan or skillet, melt the butter and add the mushrooms. Season with salt and pepper and cook until golden brown. Add the garlic, thyme and oregano; sauté until fragrant.Deglaze the pan with chicken stock. Simmer and reduce and then add the mustard. Return chicken to the pan and stir through the fresh parsley.Serve on a bed of noodles, cauliflower rice or your favourite veggies.