Pat the whole chicken dry with paper towels. Place it breast-side down on a cutting board. Using sturdy kitchen shears, cut along both sides of the backbone and remove it. Flip the chicken over and press down firmly on the breastbone to flatten it (this is called spatchcocking).

In a small bowl, combine the olive oil, minced garlic, chopped fresh rosemary, red pepper flakes, smoked paprika, lemon zest, lemon juice, salt, and black pepper. Mix well to form a paste.

Rub the spice mixture all over the chicken, making sure to get under the skin of the breast and thighs. Cover the chicken and refrigerate for at least 30 minutes, or ideally 2-4 hours, for the flavors to meld.

Preheat your oven to 400°F (200°C). Place the marinated chicken, skin-side up, on a roasting rack set over a baking sheet.

Roast for 45-55 minutes, or until the internal temperature of the thickest part of the thigh reaches 165°F (74°C) and the skin is golden brown and crispy. If the skin is browning too quickly, you can loosely tent it with foil.

Remove the chicken from the oven and let it rest on the cutting board for 10-15 minutes before carving. This allows the juices to redistribute, ensuring a tender and moist chicken. Carve into pieces and serve immediately.