Preheat oven to 400F and line a large baking sheet with parchment paper or foil.
Chop carrots in half, then again lengthwise in halves or quarters to create slivers that are about 3-4" long and 1/2" thick (see photos for reference).
Add carrots to a large bowl and drizzle over the olive oil and maple syrup. Mix well to evenly coat the carrots.
Add salt and cinnamon to the carrots and mix again.
Spread seasoned carrots evenly on the baking sheet and bake for 20-25 minutes until tender.
Candied Rosemary Hazelnuts
While the carrots are baking, make the candied hazelnuts.
Heat a non-stick pan over medium heat. Once hot, add the hazelnuts and rosemary and toast for 1-2 minutes while stirring.
Add maple syrup and continue to stir for 2-4 minutes or until all the maple syrup has solidified on the hazelnuts and they are slightly browned. Keep an eye on them during this step, as they can go from toasted to burnt pretty quickly. Once they are golden brown, finish with 1/4 tsp salt, remove them from heat, and onto a plate to cool. Spread it out so it doesn't all stick together.
Once carrots are done, top with the toasted candied hazelnut mixture to serve.