Prep leeks your leeks by cutting off roots and dark green ends starting about 1/4 inch past where the light green turns to dark green. Slice and place in colander and run under water. Rinse very well. Leeks are very sandy.
Chop 6 cloves of garlic.
Turn stove top on to medium heat.
Place 6 tablespoons of butter into a large pot. Lightly sautee prepped leeks and chopped garlic. Set some sauteed leeks aside for garnish.
Add 4 cups of chicken broth, sea salt and pepper and pinch of cayenne. Bring to a high simmer.
Add chicken and simmer for 5 minutes.
Turn heat down and add 1 1/2 cups of cream.
In a small bowl mix 3 tablespoons of cornstarch with enough cream or water to make a slurry mixture. Stir this into your soup to thicken.