Melt butter in a large skillet. Blend in flour, salt, and pepper.
Cook, stirring on low heat until bubbly. Stir broth and milk in slowly. Boil 3 minutes, stirring constantly.
Combine bread, onion, celery, salt, sage, and butter. Toss lightly to mix. Arrange in two 2-quart baking dishes. Place turkey on top. Cover with cream sauce. Mix with fork to moisten dressing. Bake at 350 F for 1 hour.