Cut the squash in half and scoop out the guts and seeds with a spoon; place them in a broiler pan and drizzle with a generous amount of extra-virgin olive oil, then sprinkle liberally with salt and pepper.
Turn the squash flesh side down and bake in the oven, uncovered, for about 20 minutes, until softened and the flesh can easily be pierced with the tip of a sharp knife.
While the squash is baking, melt the ghee in a skillet set over medium heat. Add the chopped onion, garlic, jalapeño pepper, celery and green bell pepper and cook until softened and fragrant, about 3 minutes.
Throw in the ground beef, salt, pepper, garam masala, cinnamon and turmeric and cook until the meat is completely browned and cooked through, about 5-6 minutes.
Add tahini and water and stir until well combined. Finally, toss the spinach leaves right in and stir delicately until it’s completely wilted and well distributed. Kill the heat and set aside.
When the squash is fully cooked, remove it from the oven and allow it to cool for a few minutes until you can safely handle it, then scoop out most of the flesh with a spoon. You’ll want to leave about half an inch of flesh over the skin.
Add the flesh that you just scooped out to the beef mixture and delicately mix it in.
Spoon that mixture right back into the acorn squash halves, sprinkle with the ground almonds and return to the oven for about 10 minutes, then set the oven to broil to finish browning the top.