Preheat oven to 218°C first. Peel if desired — skins are edible and fine to leave on. Cut into uniform 3/4-inch cubes; even sizing is critical so pieces cook at the same rate. Toss in a large bowl with olive oil until fully coated. Season with kosher salt, black pepper, garlic powder, and sweet paprika. Line or lightly spray your sheet pan before loading.

Spread seasoned cubes in a single layer on a sheet pan — no crowding or they'll steam instead of roast. Use two pans if needed. Place on a middle rack. Roast at 218°C for 25–35 minutes. Flip every 10–15 minutes with a thin spatula for even browning. Start checking at 25 minutes. Look for golden, crisping edges and tender centers. Smaller cubes (~1/2 inch) may finish around 20–25 minutes; larger cubes may need the full 35 minutes.

Sweet potato cubes are done when fork-tender all the way through, golden on the surface, and crisped at the edges — a fork or skewer should slide in with zero resistance. If the outside is golden but the center feels firm, return to the oven in 5-minute increments. Rest on the pan for at least 5 minutes before serving so the exterior firms up. Watch closely after the 25-minute mark — natural sugars can go from caramelized to burnt fast.