Season: Season the chicken breasts on both sides with salt and pepper. Place them in a single layer in the slow cooker.
Combine: In a mixing bowl, whisk together the chicken broth, heavy cream, Parmesan, garlic, oregano, thyme, and red pepper flakes.
Assemble: Pour the sauce mixture over the chicken in the crockpot and scatter the chopped sun-dried tomatoes evenly on top.
Slow Cook: Cover and cook on low for 4 hours or high for 2 hours. Ensure chicken reaches an internal temperature of 165°F.
Finish: 30 minutes before serving, add the butter to the pot, stirring gently into the sauce until melted.
Serve: Garnish with fresh basil or parsley and serve over your choice of pasta, rice, or mashed potatoes.