Preheat your oven to 375°F.
Let the chicken come to room temperature for at least 30 minutes and pat it completely dry with paper towels.
In a small bowl, mix together paprika, garlic powder, onion powder, salt, parsley, lemon zest, and black pepper. Divide this seasoning blend into thirds.
Combine 1/3 of the seasoning blend with the softened butter.
Spread half of the butter mixture over the outside of the chicken and the remaining half under the skin.
Sprinkle another 1/3 of the seasoning blend into the chicken cavity.
Stuff the cavity with a few slices of onion, lemon quarters, and the halved garlic head.
Prepare the vegetables by cutting the potatoes, carrots, onion, and shallot into bite-sized pieces.
Place the vegetables in a large roasting tray, drizzle with 1 tbsp olive oil, and sprinkle with the remaining 1/3 of the seasoning blend. Toss to coat evenly.
Place the seasoned chicken on top of the vegetables in the roasting tray.
Drizzle 1 tbsp olive oil over the top of the chicken and rub it all over the skin to help it crisp while baking.
Roast the chicken for about 1 hour and 20 minutes, or until the internal temperature of the thickest part of the chicken reaches 165°F.
Let the chicken rest for 10 minutes before carving.
Serve the chicken alongside the roasted vegetables, drizzled with pan drippings if desired.