Preheat oven to 350°.
Cook bacon in a large skillet over medium-high heat until crisp. Remove bacon from pan, reserving 2 teaspoons drippings in pan; set the bacon aside. Add 1 cup diced onion and diced celery; sauté for 5 minutes or until tender. Add diced green onions, garlic, fresh thyme, salt, and red pepper; sauté for 1 minute. Remove from heat.
Combine bread, onion mixture, and cooked bacon in a large bowl. Add broth, 1/4 cup water, and egg whites, stirring gently until combined. Gently fold in oysters. Spoon the mixture into an 11 x 7-inch baking dish coated with cooking spray. Cover and bake at 350° for 30 minutes. Uncover; sprinkle with cheese. Bake an additional 30 minutes or until golden brown. Let stand 5 minutes before serving.