Preheat oven to 400°F. In a large bowl, mix together all ingredients besides the sweet potatoes.
Peel sweet potatoes and chop into smaller squares. Mix them with the other ingredients, making sure to coat all of the potatoes.
Spread the sweet potatoes on a greased baking sheet and cook uncovered in the oven for about 35 minutes, flipping halfway through. Bake until fork-tender.
When done cooking, drizzle some more maple syrup on top for extra sweetness.
Notes
Optional: To be sure that the rosemary does not burn or lose its flavor, do not add it until you flip the potatoes halfway through baking.