1. 1. Cook the Pasta: Bring a large pot of salted water to a boil and cook the pasta according to the package instructions until al dente. Drain and set aside.

2. 2. Sauté the Aromatics: In a large skillet, heat the olive oil and 1 tablespoon of butter over medium heat. Add the chopped onion and sauté until translucent, about 3-4 minutes.

3. 3. Cook the Mushrooms: Add the sliced mushrooms to the skillet and cook until they’re nicely browned, about 5-6 minutes.

4. 4. Add Garlic and Mustard: Stir in the minced garlic and Dijon mustard, cooking for an additional minute until fragrant.

5. 5. Deglaze the Pan: Pour in the chicken or vegetable broth and bring the mixture to a simmer, allowing it to reduce slightly, about 2-3 minutes.

6. 6. Finish the Sauce: Stir in the remaining 1 tablespoon of butter, lemon juice, and lemon zest. Add the cooked pasta and toss everything together to coat evenly.

7. 7. Add Cheese and Garnish: Remove the skillet from heat and stir in the Parmesan cheese. Sprinkle the dish with freshly chopped parsley, and season with salt and pepper to taste.