.Place all the stock ingredients in a large, 8-qt pot. Add water to cover, leaving about an inch of space at the top. Place over low heat. Bring the water to a very low simmer. Let the stock simmer for 2 hours. The juices from the chicken should run clear. Reserve the chicken. Let the chicken cool, remove it from the bones, and dice. Remove all vegetables and strain the stock using a fine mesh strainer. Reserve 1 1/2 quarts of the stock. Place the remainder in an airtight container, and refrigerate for use at a later date.
Using a sharp knife, remove only the meat part of the kernels of corn. Once removed, milk the cream from each cob using the back side of your knife. Reserve the corn and cream for the chowder. Next, heat the bacon in a large pot over medium heat. Cook until the bacon fat is rendered and the meat is firm but not yet crisp, about 5 minutes. Add the celery, garlic and onions. Then season with a little salt and pepper. Reduce the heat to medium-low and cook, stirring occasionally, until the vegetables start to soften, about 3 minutes. Add the potatoes, corn, and thyme. Continue to cook, stirring occasionally, until the onions are soft, about 5 additional minutes.
Add the chicken broth to the pot. Bring the broth to a simmer over medium-high heat. Turn down the heat to medium and simmer until potatoes are tender, about 10 minutes. Add the cream and reserved chicken. Return the chowder to a simmer.
In a small pan over medium heat, melt the butter. Once the butter is melted, add the flour. Whisk off and on for about 3 minutes. Cook until the roux is light brown and has the smell of toasted almonds.
Add a little of the soup mixture to the roux and whisk until thickened. Add the thickened mixture to the chowder and stir until the soup is thickened. Season to taste with salt and pepper. Serve!.