Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente. Reserve ½ cup of pasta water, then drain the pasta in a colander.

While the pasta is cooking, heat olive oil in a large skillet over medium heat. Add the chopped onion and sauté for about 3-4 minutes, until softened.

Stir in the minced garlic and cook for an additional minute until fragrant.

Add the sliced mushrooms to the skillet and cook for about 5-7 minutes until they have released their moisture and started to brown.

Sprinkle in the dried thyme, stirring to combine. Pour in the vegetable broth and let it simmer for 2-3 minutes until slightly reduced.

Lower the heat and stir in the heavy cream, allowing it to heat through. Add the grated Parmesan cheese and stir until melted and smooth. Season the sauce with salt and black pepper to taste.

Add the drained pasta to the skillet, tossing to combine with the creamy mushroom sauce. If the sauce is too thick, add a little reserved pasta water to reach desired consistency.

Serve hot, garnished with fresh chopped parsley and additional grated Parmesan cheese if desired.