Season the chicken breasts with salt and pepper and place them in the slow cooker bowl
Add ½ c chicken broth and cook on high for 2 – 3 hours or low for 4 – 5 hours
When cooking time is up, remove the breasts and with two forks, shred the chicken OR cut the chicken into cubes if you prefer. Add the chicken back to the slow cooker bowl
While the chicken is cooking, wash the leeks THOROUGHLY. (see notes)
Cut off the thick, woody and tough green portions of the leeks
Slice the leeks in half, and then chop the leeks in half moon thin slices
Add the leeks, garlic, rosemary, salt and pepper to the slow cooker bowl after you have returned the shredded chicken back to the bowl
Add the rest of the chicken broth (see notes)
Cook on high for another two – 3 hours or until the leeks are tender
Add the heavy whipping cream
Cook for another half hour. Taste for seasoning
Enjoy!