Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the red potato into 1/2-inch cubes and slice the carrots into thin rounds.
Place the potatoes and carrots on the baking sheet, toss with 0.25 tbsp of olive oil and a pinch of salt and pepper, then roast for 10 minutes.
While the root vegetables roast, cut the zucchini and red onion into bite-sized pieces and mince the garlic.
Season the chicken breast evenly on both sides with half of the dried rosemary, thyme, sea salt, and black pepper.
Remove the baking sheet from the oven and move the potatoes and carrots to one side.
Add the chicken breast, broccoli florets, zucchini, and red onion to the empty space on the sheet pan.
Drizzle the remaining 0.5 tbsp of olive oil and the minced garlic over the vegetables, then sprinkle everything with the remaining herbs and seasoning.
Return the pan to the oven and roast for 18-22 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are caramelized.
Allow the chicken to rest for 5 minutes before slicing to ensure it stays juicy for serving or meal prep.