6 slices bacon 
3/4 c. chopped onion 
1/2 c. chopped celery 
1/4 c. chopped green pepper 
1 (4 oz.) can mushrooms 
1 can condensed cream of celery soup 
1 c. dairy sour cream 
1/2 c. shredded cheddar or American cheese 
3 c. cut up cooked turkey or chicken 
1/4 tsp. salt 
1/8 tsp. pepper 
2 c. Bisquick baking mix 
1/2 c. milk 
2 eggs

Heat oven to 350 degrees. Grease 2 quart round casserole. Fry bacon in 10" skillet until crisp; remove from skillet and crumble. Cook and stir onion, celery, green pepper and mushrooms in bacon fat until tender; drain if necessary. Stir in soup, sour cream, turkey, salt, pepper and bacon; heat until bubbly. Spread in casserole. Mix remaining ingredients just until moistened; spread over turkey mixture. Bake, uncovered until golden brown, 30 to 35 minutes. Serves 6 to 8.
 

Source: http://www.nancys-kitchen.com