De-Bone Chicken Thighs: De-bone chicken thighs (see Note below for video instruction on how to do this). Then, if some of the thighs are quite thick, transfer them to a storage bag, and, using a rolling pin or meat mallet, roll or pound them a few times to flatten so they cook evenly (see Note below for written instructions on how to do this).
Crisp Chicken Skin: In a large skillet over medium heat, melt 2 Tablespoons of ghee or unsalted butter. Once melted, add chicken thighs skin-side down, increase heat to high, and cook for 2 minutes before reducing heat back to medium and cooking until skin is crisped, about 1-2 minutes.
Cook Chicken: Flip chicken over and cook until chicken is cooked to an internal temperature of 165 degrees F, about 10-13 minutes. Transfer cooked chicken from skillet to a plate, loosely cover plate with foil, set aside, and allow chicken to rest. Do not discard cooking fat from the skillet.
Start Making Sauce: To the same skillet with cooking fat in it, over medium heat, add chicken broth, onion, sun-dried tomatoes, white wine (optional), garlic, Italian seasoning, salt, and pepper. Bring the mixture to a slight boil, stir, then reduce heat to low to simmer the mixture. Simmer on low heat for 3 minutes before adding grated Parmesan, heavy cream, and remaining 1 Tablespoon of ghee or unsalted butter.
Finish Making Sauce: Cook for additional 3 minutes on low heat until mixture thickens. Carefully taste test to check seasoning and, based on taste preferences, add more salt and/or pepper.
Final Steps: Add spinach and gently stir through until almost wilted, about 1 minute, before adding the cooked chicken back to the skillet and spooning the cream mixture atop the chicken.