Preheat your oven to 350°F (175°C).
Spread the cubed bread on a baking sheet and toast for 10–15 minutes until golden brown.
In a large skillet, melt the butter over medium heat. Add the onions and celery, cooking until softened, about 5–7 minutes.
Stir in the sage, thyme, salt, and pepper, then cook for an additional 2 minutes to release the herbs' essential oils.
Combine the toasted bread cubes and the sautéed mixture in a large bowl, mixing gently to distribute the flavors evenly.
Pour the broth over the mixture and fold in the beaten eggs until everything is well moistened.
Transfer the mixture to a buttered baking dish and cover with aluminum foil. Bake for 30 minutes.
Remove the foil and bake for an additional 15–20 minutes, until the top is golden brown.