Follow these step-by-step instructions to create a restaurant-quality creamy spinach and mushroom pasta right in your own kitchen.

1. Cook the Pasta: Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions until al dente. “Al dente” means “to the tooth” in Italian, and refers to pasta that is cooked through but still firm to the bite. Overcooked pasta will become mushy and lose its texture. Reserve about 1 cup of pasta water before draining. This starchy water will be used to adjust the sauce consistency later. Drain the pasta and set aside.
2. Sauté Aromatics: While the pasta is cooking, heat olive oil and butter in a large, deep skillet or Dutch oven over medium heat. The combination of olive oil and butter provides both flavor and prevents the butter from burning. Once the butter is melted and the pan is hot, add the chopped shallot and sauté for 2-3 minutes, until softened and fragrant. Sautéing the shallot first allows it to become sweet and mellow, building a flavor base for the sauce.
3. Add Garlic and Thyme: Add the minced garlic and dried thyme to the skillet and sauté for another minute, until fragrant. Be careful not to burn the garlic, as it can become bitter. Cooking the garlic briefly releases its aromatic oils and enhances its flavor. The thyme infuses the oil and butter with its herbaceous notes.
4. Sauté Mushrooms: Add the sliced mushrooms to the skillet and cook, stirring occasionally, for 8-10 minutes, or until they are browned and have released their moisture. Initially, the mushrooms will absorb the oil and butter, then they will release their water. Continue cooking until the water evaporates and the mushrooms begin to brown and caramelize. This browning process is crucial for developing the rich, umami flavor of the mushrooms.
5. Deglaze with Vegetable Broth: Pour in the vegetable broth and scrape up any browned bits from the bottom of the skillet. This process, called deglazing, adds depth of flavor to the sauce. The vegetable broth lifts all the flavorful fond (browned bits) that have accumulated at the bottom of the pan, incorporating it into the sauce.
6. Add Heavy Cream and Parmesan: Reduce the heat to low and pour in the heavy cream. Stir in the grated Parmesan cheese. Reduce the heat to low to prevent the cream from scorching or separating. Stirring constantly helps the Parmesan cheese melt smoothly into the cream, creating a luscious and creamy sauce.
7. Simmer and Thicken: Simmer the sauce gently for 5-7 minutes, stirring occasionally, until it has thickened slightly. Simmering allows the flavors to meld together and the sauce to reduce and thicken naturally. Avoid boiling the sauce vigorously, as this can cause the cream to separate.
8. Wilt Spinach: Add the chopped spinach to the sauce and stir until it wilts down completely. The heat from the sauce will quickly wilt the spinach. Stirring ensures that the spinach is evenly distributed throughout the sauce and wilts uniformly.
9. Combine Pasta and Sauce: Add the drained pasta to the skillet with the creamy spinach and mushroom sauce. Toss to coat the pasta evenly with the sauce. Ensure that every strand of pasta is coated in the delicious cream sauce.
10. Adjust Consistency: If the sauce is too thick, add a little of the reserved pasta water, one tablespoon at a time, until it reaches your desired consistency. The starchy pasta water helps to thin the sauce while also emulsifying it and making it even creamier.
11. Season and Serve: Season the pasta with salt, black pepper, and red pepper flakes (if using) to taste. Taste and adjust seasoning one last time to ensure the flavors are perfectly balanced. Garnish with fresh chopped parsley and extra Parmesan cheese, if desired. Serve immediately and enjoy!