Heat the oil in a medium pot over medium-high heat. Once the oil begins to shimmer, add the onion and celery and cook for 5-6 minutes, until the onion is semi-translucent and the celery has softened a bit.
Add the apple and cook for an additional 4-5 minutes, until softened.
Add the salt, pepper, parsley, rosemary, thyme, and sage and cook for 2-3 minutes, until the herbs are fragrant.
Add in about a ¼ of the cubed bread and 1 cup (240 ml) of the vegetable broth.
Stir well until bread cubes cook down. Continue, alternating between adding bread and broth, until everything has cooked down but the stuffing is still slightly chunky.
Transfer to a large baking dish and cover with foil.
Bake for 10 minutes, then uncover and bake for another 10 minutes, until the top is golden brown. Serve warm.