Preheat your oven to 400°F (200°C). Carefully halve the spaghetti squash lengthwise. A sharp, sturdy chef's knife works best. Use a large spoon to scoop out the seeds and stringy pulp from both halves. Discard the seeds and pulp.

Brush the cut sides of the squash halves with olive oil, then sprinkle generously with sea salt and freshly ground black pepper. Place the squash halves cut-side down on a baking sheet. Roast in the preheated oven for 35-45 minutes, or until the skin is easily pierced with a fork and the flesh is tender.

Carefully remove the squash from the oven. Let it cool on the baking sheet for about 5-10 minutes, just until it's cool enough to handle. Using a fork, gently scrape the flesh from the inside of each squash half into a large bowl. It will naturally separate into spaghetti-like strands.

While the squash cools, melt the unsalted butter in a small skillet over medium-low heat. Add the minced garlic and sauté for 1-2 minutes, until fragrant but not browned. Remove from heat.

Pour the melted garlic butter over the spaghetti squash strands in the large bowl. Add the chopped fresh parsley. Toss gently to combine, ensuring all the strands are coated. Taste and add more salt and pepper if needed.

Serve the garlic herb spaghetti squash warm, garnished with grated Parmesan cheese if desired. It makes a fantastic healthy side dish or a light meal on its own.