1. Melt butter in a Dutch oven over medium heat; add onion and celery, and cook, stirring occasionally, 8 minutes or until tender. Add mushrooms, and cook, stirring occasionally, 5 minutes. Add flour, and cook, stirring constantly, 1 minute.
2. Gradually stir in 2 cups milk; cook, stirring often, 5 minutes or until mixture is thickened and bubbly.
3. Reduce heat to low, and stir in cheese and next 5 ingredients. Cook, stirring often, 3 minutes or until cheese melts and mixture is hot.
4. Add oysters and oyster liquor, and simmer 3 minutes or just until edges of oysters begin to curl. Serve with crackers, if desired.
Note: To make ahead, prepare the stew through Step 3. Freeze the mixture in a large zip-top plastic freezer bag for up to 2 months. Thaw in the refrigerator overnight. Heat in a Dutch oven over medium-low heat 10 minutes or until thoroughly heated. Proceed with recipe as directed in Step 4.
Choosing the Best: Fresh shucked oysters are found in the seafood department of supermarkets or at seafood markets. We don't recommend substituting canned oysters in this recipe. Fresh oysters come in 12-oz. containers and range in size from standards (the smallest) to counts (the largest). Standards and selects are the most economical and are the best choices for oyster stew.