A little bit of cinnamon goes a long way in the butter used to flavor this roasted side dish.
Preheat oven to 450 degrees. On a large rimmed baking sheet, toss squash with oil; season with salt and pepper. Arrange on sheet, cut side down, and roast until easily pierced with a paring knife, 35 to 45 minutes.
In a small saucepan, melt butter over medium heat, stirring, until golden brown, 4 to 6 minutes. Immediately pour into a small bowl; stir in cinnamon. Place squash on a serving platter; top with cinnamon butter.
You can make the squash up to one day ahead. Reheat in the oven before serving.