Place 1 pound boneless skinless chicken breasts in the Crockpot and pour in 4 cups chicken broth.
Add 1 tablespoon Italian seasoning, ½ teaspoon garlic powder, ¼ teaspoon onion powder, ¼ teaspoon crushed red pepper flakes (optional), salt, and pepper to taste.
Cover and cook on high for 4 hours or low for 6 hours, until the chicken is tender.
Remove chicken, shred with two forks, and return to the pot.
Finish
Stir in 1 cup heavy cream, 1 cup marinara sauce, and 1 cup grated Parmesan cheese.
Cook on high for 15 more minutes until the cheese melts and the soup is creamy.
Notes
Leftovers keep well in the refrigerator up to 4 days.Freeze in airtight containers up to 3 months. Reheat gently until 165°F, adding a splash of broth if thickened.