Preheat oven to 350 F. Line a baking sheet with parchment paper and set aside.
Slice spaghetti squash in half horizontally, then scoop out the seeds with a spoon.
Place cut side down on the baking sheet and bake for about 1 hour or until cooked through.
Cool for 10 minutes and then shred with a fork.
Drain all of the excess water.
In a large skillet, heat olive oil over medium heat.
Add onion and cook until soft. Then add in 4 garlic and cook until fragrant.
Add sausage and break it into small pieces as it browns. Continue to cook until the meat is no longer pink, then remove the pan from heat.
Drain out the excess grease. Then add the cooked spaghetti squash to the pan. Stir to combine. Then set aside.
Mix together the cottage cheese, cream cheese, sour cream, Italian seasoning and 1 cup of shredded mozzarella in a mixing bowl.
In a baking dish, add half of the shredded spaghetti squash.
Then add the cheese mixture and the rest of the spaghetti squash.
Top with the spaghetti sauce and the remaining 2 cups of shredded mozzarella.
Bake the assembled casserole for 35-45 minutes until it's heated through and the cheese is melted. Serve and enjoy!