Preheat your oven to 425°F (220°C). Line a baking sheet with parchment for easy cleanup.
Wash the sweet potatoes well. You can peel them if you like, but I often leave the skins on for extra texture and nutrients.
Slice the potatoes into roughly 1/2-inch thick rounds or small wedges. The goal is even cooking and a good surface area for those caramelized edges.
In a large bowl, toss the potatoes with olive oil, chopped rosemary, salt, pepper, and garlic if using. Make sure every piece is lightly coated.
Spread the potatoes in a single layer on the prepared baking sheet. If they’re crowded, they’ll steam instead of roast, so give them a little space.
Roast for about 20 minutes, then flip the pieces. Roast for another 10–15 minutes, or until the edges are nicely caramelized and the centers are tender when pierced with a fork.
If you’re aiming for a toastier finish, switch to broil for 1–2 minutes at the end, watching closely to prevent burning.
Remove from the oven, drizzle with lemon juice if using, and sprinkle with cheese while warm so it melts a bit over the potatoes.
Taste and adjust with a pinch more salt or pepper if needed. Serve warm.