Preheat oven to 400°F (200°C). Add sliced onions to a baking dish with olive oil and seasonings. Toss to coat.
Slice the top off the garlic head, drizzle with olive oil, season with salt, and place cut-side up on top of the onions.
Cover with foil and bake for 1 hour, tossing every 20 minutes and adding a splash of water each time to prevent burning, until the onions are golden and jammy.
Meanwhile, cook pasta according to package instructions. Reserve up to 1 cup of pasta water before draining.
Add sun-dried tomatoes to the hot onions and remove the garlic to let cool slightly. Squeeze in the roasted garlic, add chili crisp, coconut milk, soy sauce (if using), parsley, parmesan, stir and then add cooked pasta. Toss until creamy, adding pasta water as needed to loosen the sauce. Taste and adjust seasoning.
Finish with Parmesan, extra chili crisp, and fresh parsley. Enjoy!
