In a large saucepan over medium heat, add the butter and garlic. Saute on medium heat until the garlic is translucent and lightly golden, or about 3-5 minutes.
Add the chicken broth, heavy cream, Parmesan cheese, and sun-dried tomatoes*. Continue to cook and stir until all of the Parmesan cheese is melted, then remove from heat.
Place chicken breasts in the slow cooker, then add the cream sauce, spinach, Italian Seasoning, red pepper flakes, and season with salt and pepper. Stir until combined, then cover the slow cooker.
Cook on low for 5-6 hours, or cook on high for about 3 hours. Check the internal temperature of the chicken to be sure it has reached 165 degrees F. in the thickest spots.
Turn off the slow cooker and remove the cooked chicken. Slice or dice as desired, then add back to sauce and serve over rice, zoodles, cauliflower rice, or your favorite pasta noodles. Enjoy!