Cook the chicken: Heat up a skillet for 2-3 minutes and pat the chicken dry with a paper towel. Add 1/2 of the olive oil to the pan and let it heat up for 1-2 minutes until it looks "shimmery" when you tilt the pan. Carefully add the chicken to the pan and immediately season it with salt and pepper. Let it cook on each side for 3-4 minutes over medium heat. You're looking for a little golden color on the edges. Remove the chicken from the pan (it's okay if it's not fully cooked through - you'll add it back later).

To the same pan over medium heat, add a splash of water and scrape any bits of chicken residue with a spatula. Add the mushrooms, chopped onion, garlic, salt, pepper, oregano and sage to the pan. Saute for about 10 minutes, until very fragrant.

Meanwhile, cook the spaghetti according to the package.

Add the chicken, drained tomatoes, basil, spinach, pasta water (if you remembered, if not, sub water or broth), milk and flour. Stir and bring the mixture to a low boil. Stir occasionally and cook over medium heat for 5-7 minutes or until the sauce has thickened to your desired consistency.

You can add the cooked pasta to the skillet and mix it in with the sauce and divide it between the containers OR you can divide the pasta between 3 containers and add the chicken mixture on top - up to you! Top with parmesan cheese if desired.