Preheat your oven to 300°F. Place the bread cubes on a rimmed baking sheet. Drizzle with olive oil and add a pinch of salt. Toss gently to coat. Bake for 30-35 minutes until the cubes are dry and lightly toasted, stirring every 10 minutes. Remove from the oven and let cool.
In a large skillet over medium-low heat, melt the butter. Add the chopped onion and celery with a pinch of salt. Cook until soft, about 15 minutes. Stir in the minced garlic, dried thyme, dried sage, dried rosemary, and ground black pepper, and cook for an additional 1-2 minutes.
Meanwhile, increase your oven to 375°F. In a small bowl, whisk together the eggs and warm chicken stock slowly. In a large bowl, gently combine the toasted bread cubes, cooked vegetables, and the egg-stock mixture until evenly coated. If the mixture is dry, add a splash more chicken stock.
Transfer the mixture into a greased 9x13-inch baking dish. Cover the dish with foil and bake for 30 minutes. Remove the foil and bake for another 10-15 minutes until the top is golden and slightly crisp.