01 - Set the oven to 350°F and allow it to fully preheat.
02 - Arrange acorn squash halves cut side up. Spread 1/2 tablespoon whipped butter evenly over each cut surface. Sprinkle each half generously with brown sugar and dust lightly with ground cinnamon.
03 - Transfer squash halves, cut side up, into a baking dish. Pour 1/4 cup water into the base of the pan for moisture and to prevent sticking.
04 - Cover the baking dish tightly with foil and bake in the preheated oven for 50 minutes.
05 - Remove foil and continue baking uncovered for an additional 10 minutes until the squash is fork-tender and caramelized at the edges.
06 - Remove the squash from the oven, rest for several minutes, and serve warm.