Heat a tablespoon of oil in a cast iron pan and add mushrooms and garlic. Toss the mushrooms with the Italian seasoning blend and salt on high heat for 2-3 minutes till they are golden brown and slightly crispy around the edges. Remove in a bowl and set aside.

To stuff the chicken breasts, butterfly the chicken (or slice it in half without slicing it all the way through). Sprinkle salt and pepper on both sides.

Open the chicken breast such that it looks like a butterfly. On one side, place a tablespoon or two of mushrooms, top with a handful of spinach leaves and sprinkle ¼ grated cheese. Fold the other side of the chicken breast on top and secure it in place with a toothpick.

Heat the remaining oil and butter in the same pan and place the chicken breasts. Start on high heat, then reduce to medium after a minute. Cook on each side for 6-7 minutes depending on the size. Let them rest for 2-3 minutes before serving.