Preheat oven to 400. Line a baking dish (or two) with parchment paper.

Cut spaghetti squash in half lengthwise (making 6 halves total), and scoop out the seeds. Mist lightly with an olive oil mister or cooking spray, and season generously with salt and pepper. Place squash cut side down in baking dish, and place in oven. Cook until tender, about 45 min to 1 hour, depending on the size of the squash. Remove from oven and allow to cool.

While our squash is roasting, let Instant Pot to saute mode. When add in olive oil. Then add in the onions, carrots, and celery. Saute for about 2-3 minutes.

Add in all remaining ingredients, and stir it around a bit to combine. Turn off saute and cover with lid.

Set Instant Pot to Meat/Stew mode and cook on high pressure for 35 minutes. Allow to naturally release until pressure valve is down.

Open lid and shred beef with two forks. If you would like the sauce to be thicker, just set Instant Pot back on saute mode, and cook until the sauce begins to thicken.

Once spaghetti squash is cool enough to handle, scrape the squash into strands with a fork. Transfer strands to a serving bowl, or keep in the squash shell and use as a bowl.

Top each spaghetti squash half with 1/6th of the beef ragu and sauce. Garnish with fresh parsley and grated parmesan cheese, if desired.