Preheat your oven to 450F or preferably 425F convection. Line a baking sheet with parchment paper.
In a jar with a lid, add parmesan, oil, oregano, maple, 1 teaspoon salt, onion powder, and pepper. Stir to combine.
Add the potatoes to the baking sheet and toss with 3 tablespoons of the oil mixture, using your hands to evenly coat the potatoes. Spread out into an even layer, placing the potatoes on top of any parmesan bits so the cheese doesn’t burn and you’ll get delicious golden cheesy potatoes!
Nestle the chicken into the potatoes and pat the skins dry. Season the chicken all over with remaining ½ teaspoon salt, then drizzle a teaspoon or two total of the oil mixture (try to get more oil, less cheese) on top of the chicken thighs and use your hands to rub the salt and oil all over.
Bake for 40-50 minutes, or until both the chicken and potatoes are cooked through, the chicken skin is a deep golden color, and potatoes are charred/browned in spots (cooking times will vary depending on how big your chicken/potatoes are and your oven).
To the remaining oil mixture, add the vinegar, dijon, and garlic and shake vigorously to combine.
Serve the chicken and potatoes with a side of radicchio or other greens and drizzle the dressing all over everything. Sprinkle chopped herbs over top.