Keto Tuscan Chicken

0 Pound chicken between 2 pieces of parchment paper with a meat mallet until thin.
1 Season with Italian seasoning, salt and pepper.
2 Add the olive oil to a 12-inch cast-iron skillet over medium heat.
3 When the skillet is hot and the olive oil begins to shimmer - but not smoke, add the chicken and sear on both sides until golden brown.
4 Put a lid on the top and cook until the chicken reaches an internal temperature of 160F. Use an instant read thermometer.)
5 Remove from the pan and set aside. The chicken will continue to cook as it cools and reach a safe temperature of 165F without being overcooked.
6 Add the tomatoes to the pan and saute on medium high heat until they begin to "pop".
7 Turn heat back to medium.
8 Add the butter, garlic, and onions - saute for 5 minutes stirring occasionally. Don't let the garlic scorch.
9 Add the chicken broth to the pan, scraping the bottom with a skillet.
10 Add heavy cream, Parmesan cheese, and spinach and simmer, stirring occasionally until the sauce begins to thicken.
11 Add the chicken back to the skillet, and simmer on low heat for two to three minutes or until warmed through.