Gather bread, onion, celery, butter, broth, salt, pepper, and herbs
Preheat the oven to 350°F
Cut bread into cubes
Dry the bread cubes in the oven until lightly crisp
Melt butter in a skillet
Cook chopped onion and celery in the butter until softened
Add salt, pepper, sage, thyme, and parsley
Place bread cubes in a large bowl
Add the cooked onion and celery mixture
Pour in broth gradually
Mix until evenly moistened
Add beaten egg if desired
Transfer to a greased baking dish
Bake until heated through and golden on top
Serve warm