Bring a large pot of salted water to a boil, then add the pasta and cook until al dente, about 8-10 minutes. Reserve a cup of pasta water and drain the pasta.
While the pasta cooks, heat a large sauté pan over medium heat. Add olive oil and let it shimmer. Toss in the sliced mushrooms and cook, stirring occasionally, until they release their earthy aroma and turn golden brown, about 5-7 minutes.
Add the minced garlic to the mushrooms and cook for about 30 seconds, stirring constantly, until fragrant and slightly translucent. Be careful not to let the garlic brown too quickly.
Gradually add the fresh spinach in batches, covering the pan briefly to help it wilt. Stir until the spinach is vibrant green and wilted but still tender, about 1-2 minutes.
Add the drained pasta to the mushroom and spinach mixture. Use tongs to toss everything together, allowing the flavors to meld. If the mixture looks dry, splash in a little reserved pasta water, a tablespoon at a time, until the sauce coats the pasta smoothly.
Squeeze fresh lemon juice over the pasta and sprinkle with grated Parmesan. Toss again to combine. Taste and adjust seasoning if needed—add salt or pepper as desired.
Serve immediately while warm, garnished with extra Parmesan and a twist of lemon if desired. Enjoy the bright, earthy flavors of this quick and comforting pasta.
