Preheat oven to 400°F and spray a large sheet pan with cooking spray.
In a large bowl, combine melted butter, minced garlic, Parmesan cheese, Italian seasoning, paprika, salt, and pepper.
Add halved potatoes to the bowl and toss until well coated, then spread them on one side of the sheet pan.
Pat chicken thighs dry with paper towels, then brush both sides generously with the remaining garlic Parmesan butter mixture and place on the other side of the sheet pan, skin side up.
Roast for 40-45 minutes until chicken reaches an internal temperature of 165°F and skin is crispy, and potatoes are golden brown and fork-tender.
Remove from oven, sprinkle with fresh parsley, and let rest for 5 minutes before serving.