Heat olive oil in a large skillet over medium heat.
Add the onions with salt and cook slowly, stirring often, until deeply golden and caramelized, about 30 minutes.
Stir in garlic and cook for another 1 to 2 minutes until fragrant.
Pour in the vegetable broth and let it reduce slightly.
Stir in plant-based cream and nutritional yeast, mixing until the sauce looks creamy.
Meanwhile, cook the gluten-free pasta according to package instructions until al dente.
Drain the pasta, then toss it into the pan with the onion sauce.
Season with pepper and red pepper flakes, adjusting to taste.
Serve warm with fresh parsley sprinkled over the top.