Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Peel the carrots and slice them into 1-inch diagonal pieces, and cut the chicken breast into even 1-inch cubes.
In a small mixing bowl, whisk together the maple syrup, olive oil, ground cinnamon, sea salt, and black pepper.
Place the chicken and carrots on the prepared baking sheet and pour the maple glaze over them, tossing well to ensure every piece is coated.
Spread the ingredients into a single layer, making sure they are not crowded so they roast rather than steam.
Roast in the oven for 20 minutes, then temporarily remove the tray and scatter the pecans over the top.
Return the tray to the oven for an additional 5 to 7 minutes until the chicken is cooked through and the pecans are fragrant and toasted.
Garnish the dish with finely chopped fresh rosemary and serve immediately while warm.