Preheat your oven to 425°F (220°C).

Thoroughly pat the chicken dry with paper towels to ensure crispy skin. Season the cavity and the exterior generously with the kosher salt and black pepper.

Stuff the chicken cavity with the halved lemon, halved garlic head, and two sprigs of fresh rosemary.

In a large bowl, toss the halved potatoes with the olive oil and remaining rosemary. Spread the potatoes in an even layer across the bottom of a roasting pan or large cast-iron skillet.

Place the seasoned whole chicken directly on top of the potatoes.

Roast in the preheated oven for 1 hour to 1 hour 15 minutes, or until the juices run clear and an instant-read thermometer inserted into the thickest part of the thigh reads 165°F (74°C).

Remove from the oven and allow the chicken to rest for 15 minutes before carving. Serve warm alongside the roasted potatoes.