Line a baking sheet with parchment paper. Set aside.
Chop the butternut squash into 3/4-inch cubes and arrange in an even layer on the prepared sheet pan.
Drizzle the squash with oil. Sprinkle with salt, black pepper, and nutmeg, if using. Use a rubber spatula to toss the squash until it is evenly coated in the oil.
Roast the squash on the middle rack of oven for 15 minutes.
Open the oven door and stir the squash on the tray, then continue to roast until squash is fork-tender and golden brown, about 15-20 minutes.
Check to see that squash is done. Remove from oven or add time as needed.