If bacon is uncooked: In a large skillet over medium high heat, fry bacon until brown and crispy, about 6-8 minutes. Set aside to cool.
Once bacon has been cooked: Chop into small 1/4 inch pieces.
Heat a large stockpot or Dutch oven over medium heat, melt butter. Add diced onions, stirring frequently, until onions become translucent, about 2-3 minutes. Add garlic and stir for 1 minute. Add thyme (and optional sage) and stir for 1 minute, until fragrant.
Add flour and mix until it is absorbed by the onion, garlic, thyme, and sage and becomes lightly browned, about 1 minute. Whisk in milk, chicken bouillon powder, vegetable stock, clam juice and bay leaf. Stir occasionally until slightly thickened, about 3-5 minutes.
Add potatoes into the pot. Turn heat up to high, let boil, then reduce heat and simmer until potatoes are tender, about 12-15 minutes.
Stir in half and half and clams until heated through, about 2-3 minutes. Add most of the bacon pieces to pot, reserving some for garnish. Add salt, fresh cracked black peppercorn, and optional white wine vinegar. Stir. If the soup is too thick, stir more half and half as needed until desired consistency is reached.
Remove from heat. Season with more salt and pepper, to taste. Garnish with more bacon, parsley, and torn croutons or crackers. Serve immediately.