Preheat the oven. Set your oven to 425°F (220°C).
Line a sheet pan with foil or parchment for easy cleanup, and place a wire rack on top if you have one. The rack helps the skin crisp all around.
Pat the chicken dry. Use paper towels to thoroughly dry the thighs, especially the skin. Dry skin = crisp skin. Trim any excess fat if needed.
Season the chicken. In a small bowl, mix the salt, pepper, Italian seasoning, smoked paprika, and red pepper flakes.
Sprinkle evenly over both sides of the chicken thighs.
Make the garlic-Parmesan mixture. In another bowl, stir together the melted butter, olive oil, minced garlic, and Parmesan. It should be thick but spoonable.
Coat the chicken. Place the thighs skin-side up on the rack or pan. Spoon half the garlic-Parmesan mixture under the skin, gently lifting the skin and spreading it without tearing.
Brush or spoon the rest across the top of the skin.
Roast. Bake for 30–38 minutes, depending on size. The thighs are done when the internal temperature hits 175–185°F in the thickest part and the juices run clear. Higher than 165°F is fine for thighs—they stay juicy and get more tender.
Optional broil for extra crispness. If you want deeper color, broil on high for 1–2 minutes.
Keep a close eye so the garlic doesn’t burn.
Rest and finish. Let the chicken rest for 5 minutes. Sprinkle with fresh parsley and a little extra Parmesan. Serve with lemon wedges and squeeze over the top right before eating.