Preheat the oven: Preheat the oven to 400°F (200°C). Line a baking sheet with parchment or foil.
Prepare the squash: Wash and dry the acorn squash. Slice each one in half horizontally and scoop out the seeds. Trim a small piece off the bottom of each half so it sits flat on the baking sheet.
Roast the squash: Brush the cut sides with olive oil and season with allspice and salt. Place cut side down on the baking sheet and roast for 25–30 minutes, until just tender but not too soft. Remove from the oven and let cool slightly.
Make the filling: While the squash roasts, heat 1 tablespoon of ghee in a medium pot over medium heat. Add the ground beef and onion and cook until the beef is browned and the onion has softened, about 5–7 minutes.
Add garlic and spices: Stir in the garlic, cinnamon, cumin, allspice, nutmeg, salt, and black pepper. Cook another minute until fragrant.
Add rice and stock: Stir in the rinsed basmati rice and chicken stock. Add the remaining tablespoon of ghee. Bring to a boil, then reduce to low, cover, and cook until the rice is tender, about 15 minutes.
Toast the pine nuts: While the rice cooks, melt a little ghee in a small skillet over medium heat. Add pine nuts and toast, stirring often, until golden and fragrant. Remove from heat immediately so they don’t burn — they’ll continue to darken slightly as they cool.
Finish the filling: Fluff the cooked rice with a fork, then stir in the toasted pine nuts (reserve a few for garnish), dried cranberries, and chopped parsley.
Stuff and bake: Spoon a generous amount of the rice mixture into each roasted squash half, drizzle lightly with olive oil, and return to the oven. Bake for another 20 minutes, until the squash is fully tender and the tops are lightly golden. Cover loosely with foil if they brown too quickly.
Serve: Let cool slightly, then garnish with reserved pine nuts and extra parsley. Serve warm.