Heat oven to 350° F. Spread bread cubes in one layer on 2 large baking sheets. Bake for about 15 minutes or until cubes are dry, but not browned.
Allow bread cubes to cool. Place cooled cubes in a large food processor or divide up into smaller cups and chop until crumbly.
Meanwhile, melt the butter in a large skillet over medium heat. Add the onions, sea salt and pepper; cook for 5 minutes, then add herbs and vegetable broth. Simmer then transfer to a large bowl. Add remaining ingredients; gently toss to combine.
Transfer mixture to a prepared baking dish.
Bake for 30 minutes or until golden brown.
Remove from oven; set aside to cool before serving