Tear or cut bread into cubes and leave out overnight to dry. (Alternately, place bread in a single layer on baking sheets and bake at 200º for 20 minutes.)
Preheat oven to 350º F and butter a 8" x 11" baking dish.
In a large pot over medium heat, melt 3 tablespoons butter. Add onion and celery and cook until soft and translucent, 8-10 minutes. Stir in garlic, sage, thyme, and rosemary and cook until fragrant, 1 minute more. Season with salt and pepper.
Stir in remaining 5 tablespoons butter and parsley. Once the butter has melted, turn off the heat.
Pour bread cubes into the pot and stir to coat with the butter-vegetable mixture. Stir in the chicken broth and toss well to distribute evenly.
Transfer mixture to prepared baking dish and cover with foil. Bake until cooked through, 45 minutes, then remove foil and cook until bread is golden, 15 minutes more.
Garnish with parsley and serve.