In frying pan, cook bacon until it's almost crisp. Add diced onion and continue cooking until bacon is crisp.
If you are in a bit of a hurry, you can par-boil your potatoes to help them soften up a little in a large pot of salted water. If not, skip this step and move directly to crockpot.
In large crockpot, add cooked Bacon & Onions, Potatoes, Celery, Half & Half, Milk, Clams & Clam Juice from cans (I typically use 1 can minced & 2 cans chopped, but use what you like), Bay Leaves, Salt, Pepper, Parsley, Thyme, Garlic & Butter. Stir & put lid on.
Cook on low about 4 hours if you par-poiled potatoes, 6-8 if you didn't. (Remember with soup, the longer it slow cooks, the better the flavors come together) Because this is a cream based soup, be sure to stir occasionally.
10 minutes before serving, take some of the soup broth out and put in a cup or bowl, whisk in corn starch until dissolved. Stir into soup to thicken. Thicken to your liking, remember as it cooks those last few minutes it will continue to thicken as the corn starch breaks down.
Remove Bay Leaves before serving. Add a pat of butter to the top of each bowl of chowder when you serve it.