Preheat oven to 350°F (175°C) and lightly grease a baking dish.
Place bread cubes in a large mixing bowl.
Melt butter in a skillet over medium heat. Add onion and celery and cook until soft and fragrant.
Pour the butter mixture over the bread cubes.
Add sage, thyme, salt, pepper, and parsley. Toss gently to combine.
Slowly add warm broth, stirring until the bread is moist but not soggy.
Transfer the mixture to the prepared baking dish and spread evenly.
Cover loosely with foil and bake for 25 minutes.
Remove foil and bake an additional 10–15 minutes until the top is golden.
Serve warm.