Preheat oven to 400 degrees F. Line a large baking sheet pan with foil. Set aside.
In a small bowl, mix together the salt, pepper, paprika, garlic powder and onion powder with a fork. Set aside.
Pat chicken dry with paper towels, then arrange, skin side up on the baking sheet. Drizzle with olive oil and rub into both sides. Season the back side with about a third of the spice mixture, then flip so the chicken thighs are skin side up and season with remaining spice mixture. Rub into the skin and slide your fingers under the skin to rub the spice mixture into the meat as well.
Slide the pan into the oven and roast until completely cooked through; 30-35 minutes. Internal temperature should reach 165 degrees.
Let rest for 5 minutes; garnish with fresh parsley and serve immediately.
Notes
To make this recipe with boneless, skinless chicken thighs, you'll only need about half of the spice rub and 10 minutes less cooking time.