Slice squash in half and scoop out seeds.
Bake squash in Instant Pot with 1/2 c. of water for 8 minutes or face down, on parchment lined baking sheet for 45-60 minutes in a 375 degree oven.
Let cool and scoop out insides into a large bowl. Set aside.
In a small bowl, combine onions, garlic, oregano, basil, thyme, and a pinch of salt and pepper. Mix well and saute in skillet. Once softened, add tomatoes.
Cook until most of liquid evaporates.
Combine tomato-garlic mixture, ricotta, 1 cup parmesan, and parsley into the spaghetti squash. Season to taste with salt and pepper.
Bake for 30 minutes, uncovered, in a 350 degree oven.