Preheat the oven to 425°F (220°C). Line a rimmed baking sheet with parchment paper or lightly grease it.
Wash and dry the sweet potatoes. Cut them into 1-inch cubes or 1/2-inch thick wedges for even roasting.
Place the cut sweet potatoes in a large bowl. Drizzle with olive oil, add ground cinnamon, salt, and pepper. Toss until evenly coated.
Arrange the sweet potatoes in a single layer on the prepared baking sheet, cut sides down where possible. Avoid overcrowding to encourage browning.
Roast in the preheated oven for 25–30 minutes, turning once halfway through, until edges are caramelized and centers are tender when pierced with a fork.
Remove the pan from the oven. While hot, drizzle the honey over the sweet potatoes and dot with butter if using. Toss gently to glaze (a spatula or two spoons work well).
If using, sprinkle orange zest and chopped parsley or cilantro for brightness. Taste and adjust seasoning with a pinch more salt if needed.
Serve warm as a side dish or as part of a larger spread. Leftovers keep well in the fridge for 3–4 days and can be reheated gently in the oven or skillet.