Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Peel the sweet potato and cut it into 1-inch cubes, then break the broccoli into bite-sized florets.
On the baking sheet, toss the sweet potato and broccoli with half of the olive oil and a pinch of salt and pepper.
Roast the vegetables for 20 to 25 minutes until the sweet potatoes are tender and golden brown.
Season the chicken breast on both sides with the remaining salt and pepper.
Heat the remaining olive oil in a cast-iron skillet over medium-high heat and sear the chicken for 6 minutes per side.
Reduce heat to medium, add the minced garlic, rosemary, and thyme, and cook for 2 more minutes until fragrant.
Remove the skillet from heat, drizzle the chicken with fresh lemon juice, and let it rest for 5 minutes.
Plate the lemon-herb chicken alongside the roasted vegetables and enjoy immediately.