Special equipment: a bundt pan
For the marinade: In a bowl, whisk together the oil, salt, paprika, chili powder, lemon zest and juice and garlic.
For the chicken and roasted vegetables: Put the chicken in a large resealable plastic bag, add the marinade and marinate for at least 8 hours and up to overnight.
When ready to roast, position an oven rack in the bottom third of the oven (to leave clearance for the bundt pan and chicken) and preheat the oven to 400 degrees F.
Toss the peppers, sweet potatoes and half of the fennel and onions in a bowl with the olive oil and some salt and pepper. Spread the vegetables out on a baking sheet, leaving the center clear for the bundt pan.
In the bottom of a bundt pan, add the wine, garlic, rosemary and remaining fennel and onions. Remove the chicken from the marinade (discard the marinade) and sprinkle with salt and pepper. Using a square of foil, cover the hole of the bundt. Stand the chicken upright on the bundt center over the foil. Roast until the chicken registers 165 degrees F on an instant-read thermometer, about 50 minutes. Let the chicken rest for 15 minutes before serving.
Meanwhile, strain the residual juices in the bundt pan and pour into a medium skillet. Bring to a simmer and cook until reduced by half. Season with salt and pepper. Remove from the heat and slowly whisk in the butter.
Carve the chicken and place over the roasted vegetables on a platter. Pour the pan sauce over the chicken and serve.