Preheat the oven to 400F. If your squash is tough to chop in half, pierce it a few times with a fork and microwave it for 2-3 mins, Cut the squash in half lengthwise, and scoop out the seeds and soft inside, careful not to dig in too much into the squash. Brush each squash half with olive oil or lightly dampen with water, and sprinkle with salt and pepper. Place on a parchment-lined baking sheet, with the insides facing down. Bake for 35-45 minutes, depending on the size of the squash, until the spaghetti-like strands easily pull apart.

Meanwhile, prepare the lentil bolognese. Sauté diced onions, garlic, and diced carrots in olive oil or water in a pot for 5 mins, or until fragrant and onions are translucent. Rinse and drain lentils. Add lentils and vegetable broth, bring to a boil, and simmer on low for 20 mins.

Add tomato sauce and spices. Bring to a boil, and then lower heat and simmer for 5-10 minutes. If the sauce needs to be thicker, add tomato paste. If needed, thin with some water. Remove from heat, add chopped parsley, and stir through.
Once the squash is cooked through, use a fork to scrape out the insides of the squash, and set aside the spaghetti-like strands. You can also leave them in the squash if you choose to present the dish that way. Top the spaghetti squash with the lentil bolognese and serve!