Season the chicken breasts evenly with salt and black pepper on both sides.
Heat olive oil in a large skillet or sauté pan over medium-high heat.
Add the chicken breasts to the pan and cook for 5-6 minutes on each side until golden brown and cooked through. Remove the chicken from the pan and set aside.
In the same pan, reduce heat to medium and add the minced garlic. Sauté for 1 minute until fragrant.
Add the chopped sun-dried tomatoes to the pan and cook for 2 minutes, stirring occasionally.
Pour in the heavy cream and chicken broth, stirring to combine.
Add the grated Parmesan cheese and dried Italian seasoning. Stir until the cheese melts and the sauce begins to thicken, about 3-4 minutes.
Add the fresh baby spinach and crushed red pepper flakes to the sauce. Stir until the spinach wilts, about 2 minutes.
Return the cooked chicken breasts to the pan, spooning the sauce over them.
Simmer everything together for 3-4 minutes to allow the flavors to meld and the chicken to reheat.
Serve the creamy Tuscan chicken hot, spooning extra sauce over the top.