I grew up eating squash casserole at every "big" holiday....Christmas, Easter, "special" family events. It was totally laden with calories. This one cuts the calories a bit....not totally, but a bit without sacrificing taste.
Preheat oven to 350°F Cut the squash into 1/4 inch thick slices; place in a Dutch oven. Add the onion, 1 tsp salt, and water to cover. Bring to a boil over medium-high heat, and cook for 5 minutes; drain well, and pat the squash dry with paper towels.
Stir together the grated carrots, next 3 remaining ingredients, and remaining 1/2 tsp salt in a large bowl; fold in squash mixture. Spoon into a lightly greased 2 qt oval baking dish.
Stir together the crushed ritz crackers and next 3 ingredients in a small bowl. Sprinkle over the squash mixture. Bake at 350°F for 30 to 35 minutes or until bubbly and golden brown, shielding with aluminum foil after 20 to 25 minutes to prevent excessive browning, if necessary. Let stand 10 minutes before serving.