1. Cut bread in 1/2 inch cubes to get 12 cups of bread cubes. Toast in a 350 degree oven for 10-13 minutes or until lightly browned. 2. In a large skillet melt butter over medium heat; add celery and onion and cook until tender; remove from heat. Stir in parsley, sage, marjoram, and pepper.3 3. Place dry bread cubes in a very large bowl. Add vegetable mixture. Drizzle with broth to moisten, tossing lightly. Transfer dressing mixture to a 4 to 5 quart slow cooker. 4. Cover; cook on low-heat setting 4 1/2 to 5 hours or on on high heat for 2 1/4 to 2 1/2 hours.