Cook the Pasta: Bring a large pot of heavily salted water to a rolling boil. Add pasta and cook according to package directions until al dente. Before draining, reserve at least 1 cup of the starchy pasta water. Drain the pasta and set aside.

Sear the Mushrooms: While pasta cooks, heat the olive oil and one tablespoon of butter in a large skillet over medium-high heat. Add mushrooms in a single layer (work in batches if necessary). Cook undisturbed for 3-4 minutes until deeply browned on one side. Stir and continue cooking until golden all over. Remove from skillet and set aside.

Build the Aromatic Base: Reduce heat to medium and add the remaining tablespoon of butter to the skillet. Add the diced shallot and cook for 2-3 minutes until softened. Add the minced garlic and cook for another minute until fragrant, being careful not to let it burn.

Create the Creamy Sauce: Pour in the vegetable broth to deglaze the pan, scraping up any browned bits from the bottom. Let it simmer for a minute, then slowly whisk in the heavy cream. Bring to a gentle simmer and cook for 3-4 minutes to thicken slightly.

Bring It All Together: Stir in the freshly grated Parmesan cheese until it's melted and the sauce is smooth. Season with salt and pepper. Return the seared mushrooms to the skillet, then add the drained pasta.

Finish and Serve: Using tongs, toss everything together until the pasta is thoroughly coated. If the sauce is too thick, add a splash of reserved pasta water until it reaches your desired consistency. Remove from heat, stir in the fresh parsley, and serve immediately with extra Parmesan cheese.