01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper or aluminum foil.
02 - In a large bowl, combine 2 tablespoons olive oil, minced garlic, parsley, thyme, rosemary, lemon zest, lemon juice, salt, and pepper. Add the chicken breasts and toss thoroughly to coat. Let marinate for at least 10 minutes at room temperature, or up to 2 hours in the refrigerator for deeper flavor penetration.
03 - Arrange the trimmed broccolini in a single layer on the prepared baking sheet. Drizzle with 1 tablespoon olive oil, season with salt and pepper, and toss to coat evenly.
04 - Nestle the marinated chicken breasts among the broccolini on the baking sheet, ensuring even spacing for proper roasting.
05 - Roast in the oven for 20 to 25 minutes, flipping the chicken breasts halfway through cooking. The chicken is done when the internal temperature reaches 165°F and the broccolini is tender with slightly crisp, charred edges.
06 - Remove from the oven and let the chicken rest for 5 minutes before slicing. Serve alongside the roasted broccolini with lemon wedges and a sprinkle of additional fresh herbs if desired.