1. Wash oysters under cold running water and scrub shells with a small brush to remove dirt. Transfer to a large Dutch oven and add milk, cream, thyme, and bay leaves. Bring mixture barely to a simmer over medium heat. Let gently simmer, stirring occasionally, until oyster shells open, about 15 minutes.
2. Set a colander over a large bowl. Carefully pour oysters and liquid through colander. When oysters are cool enough to handle, separate them from the shells and transfer to a small bowl; discard shells, thyme sprigs, and bay leaves. Set a fine mesh strainer over a second large bowl and pour reserved milk mixture through to catch any grit or small pieces of shell; set aside.
3. Wash and dry pot and return to stovetop. Add butter, onions, and celery and cook over medium-low heat, stirring occasionally, until onions are translucent and softened, about 10 minutes. Add flour to pot and whisk mixture until smooth and no lumps remain. Cook, stirring frequently, until mixture releases a subtle nutty aroma, about 5 minutes.
4. Slowly add reserved strained milk mixture back to pot while whisking constantly to break up any clumps. Add potatoes and bring to a gentle simmer. Cook, stirring occasionally, until chowder is thickened and potatoes are tender, 15 to 20 minutes. Stir in reserved oysters and season with salt and pepper to taste. Ladle chowder into bowls and serve with crackers.
Source: Hannaford fresh Magazine, January - February 2018