Preheat oven to 400 degrees. Place squashes, cut sides down, in a 9-by-13-inch casserole dish. Bake until tender, 35 to 40 minutes.
Meanwhile, heat oil in a 4-quart pot with a tight-fitting lid over medium-high heat. Add ground beef, a pinch each cinnamon and nutmeg, and 1 teaspoon salt. Cook, stirring frequently, until browned and cooked through, 5 to 7 minutes. Transfer beef to a bowl or plate using a slotted spoon, keeping as much cooking liquid in the pot as possible.
Add onion, and cook until slightly translucent, about 5 minutes. Add garlic, and cook until fragrant, about 30 seconds. Add remaining teaspoon salt and the bulgur, and stir to combine. Add water, and bring to a boil. Reduce heat to medium-low, cover, and cook for 15 minutes. Remove from heat, and let stand, covered, for 5 minutes. Fluff with fork, and add reserved beef, the raisins, parsley, and pine nuts.
Scrape out baked squashes, forming 1/4-inch-thick bowls, and fold flesh into bulgur mixture. Divide among squash halves, and return to oven. Bake until warmed through and tops are browned, 12 to 14 minutes.