Start by boiling a large pot of salted water. Toss in the fettuccine, cooking it just two minutes shy of the package’s al dente time. Reserve about half a cup of pasta water before draining. This starchy water will help in achieving a glossy sauce later.

Mix 1/4 cup of flour with 1/4 teaspoon of salt. Coat each chicken tenderloin evenly with the flour mixture, shaking off the excess. This thin coating ensures a perfect golden crust.

Heat olive oil and butter in a large skillet. Place the chicken in a single layer and cook until golden brown on both sides and cooked through (around 8 minutes). Remove the chicken and set it aside.

Using the same skillet (don’t wipe it clean; those brown bits are pure flavor!), sauté the chopped shallots for about a minute. Add the cremini mushrooms and cook until they’re tender and slightly browned at the edges.

Pour Marsala wine into the skillet, scraping up any browned bits stuck to the pan. This deglazing process adds depth to the sauce. Cook for a few minutes until the wine reduces slightly. Stir in chicken stock, heavy cream, Italian seasoning, garlic powder, and black pepper. Bring it to a gentle boil, then reduce the heat to medium.

Make a slurry by whisking the remaining two tablespoons of flour with a small amount of water, then add it to the skillet. Stir the mixture to thicken the sauce. Toss in the spinach and cook until it’s wilted.

Return the chicken to the skillet along with the cooked pasta. Toss everything together gently until the sauce coats every strand and tender piece. Sprinkle in the freshly grated Parmesan and mix well. If the sauce is too thick, incorporate a few tablespoons of reserved pasta water.

Remove the skillet from the heat, then garnish the dish with fresh parsley before serving. Comfort food, done!