Step 1: Preheat your oven to 425°F (220°C) and line a large rimmed baking sheet with parchment paper or lightly grease with oil.
Step 2: In a large bowl or directly on the pan, toss the sweet potatoes, parsnips, and Brussels sprouts with 2 tablespoons of olive oil, rosemary, salt, and pepper until well coated.
Step 3: Pat the chicken thighs dry with a paper towel. In a small bowl, whisk together the remaining olive oil, maple syrup, smoked paprika, and minced garlic.
Step 4: Rub the chicken thighs with the maple-garlic mixture, ensuring the skin is well-covered for maximum flavor and crispness.
Step 5: Arrange the chicken thighs on the sheet pan, nestling them among the vegetables. Ensure the vegetables are spread in a single layer to allow for proper roasting.
Step 6: Roast in the preheated oven for 30-35 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and golden brown.
Step 7: Remove from the oven and let rest for 5 minutes. Garnish with additional fresh herbs and serve warm.