Preheat oven to 375 degrees F. Line a baking sheet with parchment paper.
Carefully cut stem end off of the spaghetti squash and discard. Cut squash into approximate 1″ rings, width-wise. With a spoon or tip of a knife, gently remove seeds and pulp from each ring; discard.
Place spaghetti squash rings laying down on prepared baking sheet. Bake in oven for about 40-45 minutes or until strands separate easily when scraped with a fork.
While the spaghetti squash is baking, cut your bacon into pieces and cook in a large skillet over medium heat, moving and turning frequently, until bacon is fully cooked and crispy. With a slotted spoon, remove bacon pieces from skillet and set aside.
Remove the spaghetti squash from the oven and allow to cool slightly. Remove shells of each ring and separate stands with a fork. Place strands in a large bowl.
Add butter to your warm spaghetti squash (if your strands have cooled too much, heat in the microwave a bit) and toss with the strands until the butter is fully melted and incorporated. Stir in parmesan cheese and bacon crumbles. Season with salt and pepper and serve.