Halve the squash lengthwise; remove seeds. Place squash, cut side down, in a 2-quart rectangular baking dish. Bake, uncovered, in a 350 degree F oven about 30 minutes or until tender.
Meanwhile, in a large skillet cook pears, green onion, and garlic in hot oil until tender but not brown. Remove from heat. Stir in ricotta cheese, cheddar cheese, raisins, pine nuts or pecans, lemon peel, and nutmeg. Turn squash, cut side up, in baking dish. Season with salt and pepper. Spoon the cheese mixture into the baked squash, mounding as necessary. Continue baking for 20 to 25 minutes more or until heated through. Makes 4 main-dish servings.