Preheat the oven to 425°F (220°C). Line a sheet pan with parchment paper for easy cleanup.
Pat the chicken pieces dry with paper towels to ensure crispy skin. Place them on the prepared sheet pan, skin-side up.
Scatter the sweet potato chunks around the chicken on the pan, spreading evenly for uniform roasting.
In a small bowl, mix the minced garlic, olive oil, chopped rosemary, salt, and pepper to create a fragrant marinade or basting mixture.
Brush or drizzle half of the mixture over the chicken skin and sweet potatoes, using a brush or spoon to evenly coat the surfaces.
Place the sheet pan in the oven and roast for about 25 minutes, or until the chicken skin is golden and crispy, and the sweet potatoes start to caramelize and soften.
Remove the pan from the oven and baste the chicken and sweet potatoes with the remaining marinade to keep everything flavorful and moist.
Return the pan to the oven and roast for another 15–20 minutes, until the chicken reaches an internal temperature of 165°F (74°C), and the vegetables are richly browned and tender.
Remove the pan from the oven and let the dish rest for about 5 minutes; this helps juices settle and makes serving easier.
Serve the roasted chicken with the sweet potatoes, garnished with a sprig of rosemary if desired, and enjoy the warm, comforting flavors and vibrant colors.