Bake the spaghetti squash: Preheat your oven to 375°F. Use a very sharp paring knife and poke the spaghetti squash all over, at least an inch deep, about 12 cuts (this is to prevent the pressure from building up as the squash cooks).
Place the squash in a roasting pan or rimmed baking sheet and bake in the oven for one hour.
Remove from the oven and let rest for a few minutes. Then cut the squash in half, lengthwise. (If the squash is not easy to cut, return it to the oven for another 15 minutes.)
Scoop out the seeds, discard (or save to roast later - see roasted pumpkin seeds recipe).
Scrape out the spaghetti squash strands: Use a fork to scrape the inside flesh of the squash into long thin strands.
Place the spaghetti squash strands in a large bowl and set aside.
Heat olive oil in a large sauté pan on medium heat.
Add the garlic, chili pepper flakes, and rosemary and cook for about 30 seconds, until fragrant. Do not let the garlic brown.
Add the spaghetti squash to the pan and toss to coat with the oil and garlic mixture.
Add the chopped fresh chard leaves and parsley and toss with the spaghetti squash. Cook until the chard leaves have wilted, a few minutes.
