Boil pot of salted water for pasta; cook pasta according to directions on the box.
Heat the oil in a large skillet over medium heat.
Season the chicken thighs with salt and pepper.
Place them in the hot skillet skin side down. Cook until the skin is crispy and golden brown, approximately 4-5 minutes. Flip the chicken over and continue cooking for an additional 4-5 minutes.
In a small bowl, whisk together chicken stock and relish until combined.
Pour the mixture into the skillet; bring to a boil. Turn the heat to low and simmer for 15-17 minutes or until the chicken is cooked through.
In a separate bowl, mix the butter and cornstarch together to form a paste. Stir the butter mixture into the sauce and continue cooking until thickened. Stir in the spinach.
Sprinkle the chicken with parsley and serve over the pasta. Serve immediately.
