Preheat oven to 400°F (200°C). Line a large 18x13-inch rimmed baking sheet with parchment paper or heavy-duty aluminum foil for zero-mess cleanup.

In a medium bowl, whisk together the pure maple syrup, Dijon mustard, whole grain mustard, olive oil, minced garlic, apple cider vinegar, chopped rosemary, smoked paprika, salt, and black pepper until emulsified and glossy.

Place the cubed sweet potatoes on the prepared sheet pan. Drizzle with 1 tablespoon olive oil, sprinkle with salt and pepper, and toss to coat evenly. Spread into a single layer and roast for 10 minutes to give the potatoes a head start.

While the potatoes pre-roast, pat chicken thighs dry. Toss chicken in half of the maple mustard glaze, reserving the remaining half for basting.

Carefully remove the sheet pan from the oven. Push sweet potatoes slightly to the side, nestle the glazed chicken thighs onto the pan, and scatter the fresh broccoli florets around the empty spaces.

Return the pan to the oven and roast for 20 minutes. Brush the remaining maple mustard glaze generously over the chicken thighs.

Switch oven to broil on high for the final 2 to 3 minutes until the chicken reaches an internal temperature of 165°F (74°C) with deeply caramelized, bubbly edges and the broccoli florets are lightly charred and crisp-tender.

Remove from the oven, let rest for 5 minutes, garnish with fresh rosemary, and serve hot directly from the pan.