Preheat the oven to 425.
Rinse and pat dry the chicken thighs. Season generously with salt and pepper.
Heat a large cast iron skillet over medium-high heat. Lay the bacon down on the pan in a single layer. Cook, flipping once, until fully cooked and crisp.
Lower the heat to medium, removing the pan from heat for a minute or so if it’s smoking. Add the chicken thighs to the pan skin side down and cook for 5 minutes. Flip and cook for 5-8 more minutes, or until fully cooked through. Remove the chicken from the pan. Set aside.
Add the onion and tomatoes and cook until the onions are tender and translucent and the tomatoes are slightly blistered, about 4-7minutes. Add the garlic and continue to cook, constantly stirring until fragrant, about 2 minutes.
Stir in the cream of chicken, chicken broth, Italian seasoning, and spinach to the pan. Mix to combine and continue to cook until the spinach is wilted and tender. Add in the parmesan cheese. Allow the sauce to simmer for a further minute until cheese melts through the sauce.
Add the crumbled bacon and cooked chicken back into the pan; sprinkle with chili pepper flakes (if using), and spoon the sauce over each chicken thigh.
Add the skillet to the oven for about 10-15 minutes until the chicken is completely cooked through then serve over pasta, rice or steamed veggies and enjoy.