Cut each acorn squash in half and remove the seeds. Slice a little off the bottom of each half so that they will sit evenly in a casserole dish.
Place acorn squash halves upside-down in a casserole dish. Place 1/2 C. of water in the bottom of the pan, and cover with foil. Bake at 350 degrees for 15 minutes. Meanwhile, peel, core, and slice the apples and set aside. After 15 minutes, remove the acorn squash from the oven and also remove the foil. Fill the acorn squash cavities with the slices of apple. For each acorn squash half, place 1 t. of margarine on top of the apple, 1 T. raisins, and sprinkle with a little nutmeg and salt. Add more water to the pan if needed. Bake an additional 20-30 minutes or until apples and acorn squash are tender.