Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper for easier cleanup, if desired.
In a mixing bowl, combine the cubed sweet potatoes, olive oil, maple syrup, ground cinnamon, and salt. Toss well until the sweet potatoes are evenly coated.
Spread the sweet potato mixture evenly on the prepared baking sheet in a single layer.
Roast in the preheated oven for 20 minutes, then remove and stir to ensure even cooking.
Add the chopped walnuts to the sweet potatoes and return to the oven for an additional 10 minutes, or until the sweet potatoes are tender and slightly caramelized.
Remove from the oven and let cool slightly. If desired, sprinkle with fresh parsley before serving.
For added flavor, consider incorporating a pinch of nutmeg or some chili powder for a spicy kick.
Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in the oven to maintain crispness.