Bring a large pot of salted water to a boil. Add the fusilli and cook according to package instructions until al dente, usually about 8–10 minutes. Drain the pasta, reserving about ½ cup of pasta water, and set aside.
In a large skillet, heat the olive oil over medium heat. Add the diced onion and sauté for 3–4 minutes until they become translucent. Stir in the minced garlic and cook for another 1 minute, until fragrant.
Add the sliced mushrooms to the skillet. Cook for 7–8 minutes, stirring occasionally, until the mushrooms release their moisture and become golden brown. This step develops deep umami flavor, so don’t rush it!
Sprinkle the dried thyme and paprika over the mushrooms, stirring to coat evenly. Pour in the vegetable broth and soy sauce. Let it simmer for 5 minutes, allowing the sauce to reduce slightly and the flavors to meld.
Reduce the heat to low and stir in the coconut milk. Let the sauce gently simmer for another 5 minutes, stirring occasionally, until it thickens to a creamy consistency. Season with salt and pepper to taste.
Add the cooked fusilli to the skillet with the sauce. Toss everything together, adding a splash of reserved pasta water if needed to loosen the sauce. Cook for 1–2 minutes more so the pasta soaks up the sauce.
Remove from heat and sprinkle with freshly chopped parsley. Serve immediately, perhaps alongside a crisp green salad or your favorite crusty bread.