Start by boiling water in a large pot and adding 2 teaspoons of kosher salt. The water is ready when it starts to bubble vigorously. Add the pasta and cook until it is al dente, being careful not to overcook it, or it will turn mushy.
Heat 3 tablespoons of olive oil in a large skillet over medium heat. Once warmed, add the finely diced shallot and minced garlic. You will smell the fragrant aroma filling the kitchen. Watch closely, as burnt garlic can ruin the dish.
Once the shallot is translucent, add the baby bella mushrooms. Spread them out in a single layer to ensure they sear nicely. Let them brown beautifully, adding depth to the dish. Avoid stirring too much, or they will not caramelize properly.
Sprinkle in 1/2 teaspoon of red pepper flakes if you prefer a bit of spice, and season with the remaining kosher salt and black pepper. The flavors will start to meld. Be cautious with the salt; you can always adjust it later.
Stir in the fresh baby spinach and cook until it wilts down. The vibrant green will contrast well with the mushrooms. If it does not wilt quickly, cover the skillet briefly to trap steam and speed up the process.
Gently pour in the 1/4 cup of dry white wine, letting it simmer for a couple of minutes. This step deglazes the pan, releasing the flavorful bits stuck at the bottom. Keep an eye on it to prevent it from boiling away completely.
Once the pasta is cooked, reserve some water, then drain it and add it to the skillet with the spinach and mushrooms. If the mixture feels sticky, add a splash of reserved pasta water to loosen it.
Sprinkle the grated parmesan cheese over the pasta and mix everything together. It should come together in a creamy-like sauce. Add more cheese if desired, but remember to taste it first to avoid making it too cheesy. Enjoy!