Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel and chop the carrots and parsnips into 1-inch chunks, ensuring they are uniform in size for even cooking.
Mince the fresh garlic cloves and finely chop the rosemary and thyme leaves.
In a large bowl, toss the chopped root vegetables with half of the olive oil, half of the minced garlic, and a pinch of salt and pepper.
Place the chicken breast on the prepared baking sheet and rub with the remaining olive oil, garlic, rosemary, thyme, salt, and pepper.
Arrange the seasoned vegetables around the chicken in a single layer on the baking sheet.
Roast in the oven for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and golden brown.
Remove from the oven and drizzle the lemon juice over the chicken and vegetables before serving.