Cook bacon until it's crispy.
While the bacon is cooking add onion, clams, celery, chopped potatoes, clam juice, broth, seasonings & butter to slow cooker & cook on high 3-4 hours or on low 6-7 hours
When bacon is done - chop & add to soup
During the last hour - add half & half.
In a separate bowl combine cornstarch & milk - add to soup & allow to continue to cook & to thicken
In the last 1/2 hour - add potato flakes 1/2 a cup at a time - waiting about 10 minutes before adding more until you reach the thickness you desire
Ladle out into bread bowls, top with some of the bread you removed from your bread bowl & enjoy