Melt butter in a saucepan over medium-low heat. Stir cinnamon and brown sugar through the melted butter; remove from heat and stir crushed saltine crackers into the butter until moistened.
Pour enough water into a baking dish to be about 1 inch deep.
Lay the acorn squash into the water with the rounded sides down. Fill the cavity of the squash with the saltine cracker mixture.
Bake in the preheated oven until the squash is easy to pierce with a fork, about 45 minutes.
