Finely chop the onion  and celery.

Cut the baguette into small cubes. 

To a large deep skillet on medium heat, add the oil, onion and garlic.

Add the celery. Season with rosemary, thyme, fennel, sea salt, pepper.

Pour the vegetable broth into the skillet. Mix to combine.

Add the baguette cubes. Gently stir to combine.

Transfer to a large casserole dish. Cover with foil. Bake until crispy and golden.