Heat the oil: In a large skillet, heat 2 tablespoons of olive oil over medium heat.

Cook the chicken: Add the chicken pieces to the skillet and cook for about 5-7 minutes, stirring occasionally, until the chicken is browned on all sides and fully cooked.

Sauté the garlic: In the same skillet, add the minced garlic and cook for 1 minute, or until fragrant, being careful not to burn it.

Add the tomatoes: Stir in the diced tomatoes (with their juices), Italian seasoning, and red pepper flakes if using. Allow it to cook gently for approximately 5 minutes, giving the flavors time to blend and harmonize.

Cook the spinach: Add the chopped spinach to the skillet and cook for another 2-3 minutes, until the spinach is wilted.

Combine chicken and spinach: Return the cooked chicken to the skillet and stir to combine everything. Season with salt and pepper to taste.

Add Parmesan cheese: Sprinkle the grated Parmesan cheese over the mixture and let it melt into the sauce for about 1 minute.

Garnish and serve: Garnish with fresh basil or parsley, if desired, and serve warm.