Preheat Oven to 375°F. Oil a sheet pan with olive oil.
Carefully cut spaghetti squash in half lengthwise. Scoop out the seeds and connecting strands, then place cut side down on the prepared sheet pan.
Bake for 45 minutes, or until the squash flesh becomes tender and separates easily into strands with a fork. Finish by gently loosening and removing the "spaghetti strands" from the shells. Set aside.
Heat large pan on medium-high heat. Melt butter, then add garlic. Cook garlic until fragrant and translucent. Don't let the garlic burn.Add spaghetti squash strands and toss with the garlic butter. Don't overcook the spaghetti squash strands, especially if they’re already too soft or else they'll become mush.
Remove the pan from the heat, add parmesan cheese and season generously with salt and pepper to taste. Gently stir to combine the cheese and to let it melt. Add chili flakes and chopped parsley, then serve warm. If you want to add extra parmesan for topping, go for it!