Place a large rimmed sheet pan in the oven and heat to 425°F.
Peel and seed the squash, then cut the flesh into 3/4-inch cubes. Pat away surface moisture.
Toss squash with olive oil, salt, garlic powder and pepper until every cube has a light sheen.
Carefully spread the squash on the hot pan in one layer, leaving visible space between pieces.
Roast 15 minutes, turn the cubes, then roast 10 to 18 minutes more until browned on two sides and tender through the center.
Add thyme and optional maple syrup during the final 3 minutes. Taste and adjust salt after roasting.