Slice your onion thinly, mince the garlic, and measure out all seasonings. Bring cream or coconut milk to room temperature.
Heat 2 tbsp butter and 1 tbsp olive oil in a large skillet over medium heat. Add onions and cook for 15-20 minutes, stirring occasionally, until golden and jammy. Add water if they start sticking.
While onions are caramelizing, boil a pot of salted water and cook pasta until al dente. Drain and reserve pasta water.
When onions are deeply golden, stir in minced garlic and all seasonings. Let bloom for a minute, then add chili crisp and sauté for a minute. Pour in cream or coconut milk and simmer for a few minutes. Add grated Parmesan cheese.
Add cooked pasta to the sauce and toss to coat. Use reserved pasta water to loosen if too thick, aiming for a silky consistency.
Serve hot with an extra spoon of chili crisp on top and fresh parsley if desired.
