Preheat oven to 425°F. Mix together the oil, spices, garlic and salt in a small bowl.
Place the sweet potato cubes in a baking dish large enough that they fit in a single layer. Toss the cubes with the seasoned oil in the pan until the potatoes are evenly coated. Bake in preheated oven for about 45 minutes, until pieces are fork-tender, stirring one or twice to ensure it cooks evenly.
Remove from oven and transfer to a serving dish or individual plates, and serve immediately.