Preheat oven to 425 degrees.
Peel and dice sweet potatoes into 1/2-inch cubes.
Pour maple syrup, olive oil, salt and pepper into a gallon-size bag (a large bowl works well, too) and squish with your fingers until well combined.
Add sweet potato cubes to the bag, seal the bag, and shake well to coat.
Pour the sweet potatoes onto a parchment-lined sheet pan in a single layer.
Bake about 40 minutes, stirring gently every 10-15 minutes. Sweet potatoes are done when they are fork-tender and caramelized with brown edges.