Heat a large soup pot or Dutch oven over medium heat then add the bacon. Cook until crisp then transfer to a paper towel lined plate, reserving one tablespoon of drippings in the pot.
Add the diced carrots, celery and onion, lightly season with salt and pepper and cook 2-3 minutes or until the carrots have started to soften. Stir in the thyme and grated garlic and cook one more minute.
Fold in the diced potatoes, bottle of clam juice and chicken stock. Season with Old Bay then cover and bring to a boil.
Once it's boiling reduce the heat to low and simmer 5 minutes or until the potatoes and carrots are tender, stirring occasionally.
In a medium bowl, whisk the flour and half and half together then pour into the pot whisking to blend. Simmer uncovered 5-7 minutes or until it thickens, stirring frequently.
Add the clams and their juices then rough chop the bacon and fold it into the chowder (optional: reserve some of the bacon for garnish). Continue cooking over low heat 2-3 minutes then stir in the parsley. Taste and adjust salt and pepper. Serve hot.