Step 1: Thinly slice the mushrooms to about half an inch thick. This allows them to cook evenly and absorb all the delicious flavors. Set them aside for later.
Step 2: Coarsely chop the rotisserie chicken into small, bite-sized pieces. This ensures that every forkful of pasta will be packed with flavor.
Step 3: If you’re adding baby spinach, coarsely chop it as well. You can also leave it whole if you prefer. It’s a versatile ingredient and will wilt down nicely in the heat of the pasta.
Step 4: Heads-up: Make sure to save some of the pasta water! Don’t drain it all. You'll need this starchy water later to help create a nice creamy sauce.
Step 5: Bring a large pot of water to a rolling boil. Once it’s boiling, generously salt the water. A good ratio is about one teaspoon of salt for every four cups of water. This step is crucial as it enhances the flavor of the pasta.
Step 6: Cook the fettuccine according to the package directions, but aim for one minute less than directed. This will help achieve the perfect texture. Before draining, remove one cup of the pasta water and set it aside.
Step 7: Drain the pasta and set it aside, but don’t forget about that saved pasta water!
Step 8: In a large skillet or pot (I prefer a deep cast-iron skillet), heat it over medium heat. Add 2 tablespoons of butter along with 1 tablespoon of olive oil. Once the butter has melted and starts to bubble, you’re ready to add the next ingredient.
Step 9: Add the sliced mushrooms to the skillet. Cook them, stirring occasionally, until they start to turn a lovely golden brown and all their moisture evaporates, which should take around five minutes.
Step 10: Season the mushrooms with salt and pepper to taste, about a quarter teaspoon of salt and half a teaspoon of pepper works well. Then, sprinkle in the Italian seasoning for that aromatic boost.
Step 11: Once the mushrooms are golden and fragrant, add the remaining 1 tablespoon of butter and the minced garlic. Stir everything together for an additional one to two minutes until everything is beautifully golden and aromatic.
Step 12: Now, let’s build our sauce! Lower the heat and add the Boursin cheese, chopped chicken, and the hot, drained pasta into the skillet. Using tongs, toss everything together while gradually adding small amounts of the reserved pasta water. I usually start with about half a cup and add more as needed.
Step 13: Incorporate the Parmesan cheese into the mixture too, adjusting with more pasta water if necessary, until the sauce is creamy and clings to the pasta perfectly. This is where the magic happens!
Step 14: Add the spinach to the skillet and gently toss everything to wilt the greens. This process shouldn't take long. Once wilted, remove the skillet from heat.
Step 15: Finally, taste the pasta and adjust seasoning with more salt and pepper if needed until the flavors sing. Serve immediately, garnishing with more Parmesan and fresh parsley if desired.
