Bring a large pot of salted water to a rapid boil. Add your uncooked pasta and cook according to package instructions until al dente, usually about 8-10 minutes. Stir occasionally to prevent sticking. Once done, reserve a cup of pasta water and drain the rest, letting the pasta sit in the colander while you prepare the sauce.

In a large skillet, heat 2 tablespoons of olive oil and 1 tablespoon of butter over medium-high heat. Once hot and shimmering, add the chopped onion and sauté for about 3-4 minutes until softened and translucent. Next, introduce the sliced cremini mushrooms, cooking for 8-10 minutes until they release their moisture and turn a rich, golden brown.

Stir in the minced garlic and Dijon mustard, cooking for an additional minute. Keep an eye on the skillet—the garlic should become fragrant but not browned.

Pour in 1/4 cup of chicken broth while scraping the bottom of the skillet to deglaze any brown bits. Add the lemon juice and zest, allowing the mixture to bubble for about one minute.

Remove the skillet from heat and mix in the freshly grated Parmesan cheese and chopped parsley. Stir until the cheese melts and the sauce becomes creamy. If the sauce appears too thick, add a splash of reserved pasta water to achieve your desired consistency.

Before draining the pasta, add a splash of the hot pasta water directly into the sauce and stir to combine. Drain the pasta well, then add it to the skillet with the Garlic Mushroom sauce. Toss everything together gently until the pasta is evenly coated.

Taste and adjust seasonings with salt and pepper as desired. Serve your Garlic Mushroom Pasta hot, garnished with additional parsley if you like.