Preheat your oven to 275°F. Tear the brioche bread into approximately 1-inch chunks or cubes. Spread them in an even layer on a baking sheet, then bake for 45 minutes.
Combine the low-sodium chicken broth, eggs, diced fresh parsley, sage, rosemary, salt, and pepper in a mixing bowl. Whisk until fully incorporated and set aside.
Melt the stick of butter over low to medium heat in a large sauté pan. Add the chopped celery and onion. Sauté until the celery and onion are soft and fragrant, about 10 minutes. Remove from heat and set aside.
Transfer the toasted bread to a large mixing bowl. Pour the bowl of liquid ingredients (broth, eggs, herbs, seasonings) and the sautéed onions and celery over the brioche bread cubes. Mix until fully combined.
Bake the stuffing in your preheated 350°F oven for 40 minutes, covered. Uncover, and bake for another 25-30 minutes, until the top is golden brown and crispy.