Preheat your oven to 425°F (220°C). Place a large rimmed metal sheet pan inside the oven while it preheats so the pan gets sizzling hot.

Pat the chicken thighs thoroughly dry with paper towels and season all over with half of the salt and black pepper. Toss the cubed sweet potatoes and halved Brussels sprouts with the olive oil and remaining salt and pepper.

Carefully remove the hot sheet pan from the oven. Arrange the chicken thighs skin-side up on one side and spread the sweet potatoes and Brussels sprouts cut-side down in a single layer. Roast for 20 minutes.

While the chicken roasts, whisk together the honey, melted butter (or olive oil), apple cider vinegar, minced garlic, chopped rosemary, and red pepper flakes in a small bowl.

After 20 minutes of roasting, brush the honey garlic glaze generously over the crispy chicken thighs and drizzle the remaining glaze over the sweet potatoes and Brussels sprouts.

Return to the oven for 8-10 minutes until the chicken reaches an internal temperature of 175°F (80°C), the skin is deeply caramelized, and the sweet potatoes are fork-tender. Serve warm.