Heat the oven to 375 F and line a large, rimmed baking sheet with foil.
Slice the acorn squash into 3/4-inch rounds. Cut the center soft pulp out of the center of each round to make the rings.
Arrange the rings on the baking sheet.
Combine the maple syrup, melted butter, brown sugar, cinnamon, nutmeg, and salt in a small saucepan and heat over medium-low heat until the sugar is melted. Brush some of the mixture over the squash rings, saving the rest for basting.
Roast the squash for 25 to 35 minutes, basting with the maple syrup mixture occasionally, until fork-tender.