Preheat oven to 400. Spray a 9X13 baking dish with non stick spray.
Season chicken with Italian seasoning and salt and pepper to taste.
Melt 1 Tbsp butter in a large skillet over medium high heat. Add chicken and sear both sides until golden brown - about 2-3 minutes per side. Remove from pan
In the same pan, melt 1 more tablespoon of butter. Stir in spinach and cook, stirring occasionally, until it begins to wilt, about 2 minutes. Set aside
To make the garlic parmesan sauce, melt remaining 3 Tbsp butter in the skillet over medium heat. Add garlic an cook stirring frequently, until fragrant, about 1 minute. Whisk in flour until lightly browned, about 1 minute.
Gradually whisk in chicken broth, thyme and basil. Cook, whisking constantly, until incorporated, about 1-2 minutes. Stir in half and half and parmesan until slightly thickened, about 1-2 minutes. If the mixture is too thick, add more chicken broth as needed, season with salt and pepper to taste.
Place chicken in a single layer into the prepared baking dish. Top with potatoes, spinach and cream sauce.
Place into oven and roast until completely cook through, reaching an internal temperature of 165 degrees, about 25-30 minutes.
Serve immediately, garnished with parsley if desired