Arrange a rack in the middle of the oven and heat the oven to 400ºF. Line a rimmed baking sheet with aluminum foil and fit a wire rack inside.
Prepare 2 pounds chicken wings if the wings are whole and not yet separated: Use a chef's knife or kitchen shears to cut through the first joint of each wing to remove the wing tip. Discard or freeze the wing tips for stock. Cut through the second joint to separate the wing into the forearm (flat) and upper arm (drumette) sections (20 to 24 pieces total).
Pat the wings dry with paper towels and place in a large bowl. Add 1 (1-ounce) envelope onion soup mix and 1 tablespoon olive oil. Toss with your hands until the chicken is evenly coated. Place on the wire rack in a single layer, spacing them evenly apart.
Roast until the wings are cooked through and the skin is crispy, 40 to 45 minutes. A few minutes before the wings are ready, melt 2 tablespoons unsalted butter. Set aside to cool slightly.
Transfer the wings into a large, clean bowl. Add the melted butter and 1 tablespoon of chopped fresh parsley, and toss until well-coated. Transfer to a large plate or platter and garnish with the remaining 1 tablespoon of chopped fresh parsley.
