Slide a heavy-rimmed baking sheet onto the middle rack and preheat the oven to 400°F. Tip: a preheated pan jump-starts browning.
Peel the sweet potatoes and cut into 1/2-inch cubes. Rinse briefly, then pat very dry with towels to remove surface moisture.
In a large bowl, whisk together the olive oil, maple syrup, cinnamon, ginger, salt, and black pepper.
Add the sweet potatoes to the bowl and toss with about half of the spiced oil until evenly coated; reserve the remaining mixture.
Carefully spread the coated potatoes on the hot baking sheet in a single layer. Roast for 15 minutes without stirring to develop color on the bottoms.
Remove the pan, drizzle and toss the potatoes with the remaining spiced oil, then increase oven temperature to 450°F. Return to the oven and roast 10–12 minutes more, until the edges are deep golden and the centers are fork-tender.
Optional finish: broil on high for 1–2 minutes for extra caramelization, watching closely. Taste and adjust salt if needed, then serve hot.