Bring a large pot of salted water to a rolling boil, then add the pasta. Cook according to package instructions until al dente, about 1-2 minutes less than recommended. Drain the pasta, reserving about 1/4 cup of pasta water, and set both aside.
While the pasta cooks, heat a large skillet over medium-high heat. Add the olive oil and let it shimmer as you add the sliced mushrooms. Sauté undisturbed for 3-4 minutes, allowing them to brown and release their earthy aroma.
Stir the mushrooms and add the crushed or minced garlic. Cook together for about 30 seconds until fragrant, making sure the garlic doesn’t burn, which would turn bitter.
Gradually add the fresh spinach in batches, stirring until each addition wilts and shrinks down, revealing its vibrant green color. Cook for 1-2 minutes until fully wilted but still bright.
Pour in about 1/4 cup of the reserved pasta water, scraping up any browned bits from the bottom of the pan. Stir to create a light sauce that coats the mushrooms and greens.
Add the drained pasta to the skillet, tossing gently to coat all the noodles with the flavorful mixture. Cook together for 1-2 minutes until heated through and sauce thickens slightly.
Finish by squeezing fresh lemon juice over the pasta, then sprinkle with freshly grated Parmesan cheese if desired. Taste and season with salt and pepper as needed.
Serve immediately on warm plates, garnished with extra cheese or a lemon wedge for an added zing. Enjoy the tender pasta with earthy mushrooms and bright greens in every bite.
