Preheat oven to 350°F. In a large bowl, mix all ingredients except the crabmeat and ¼ cup fontina and ¼ cup parmesan until well combined. Gently fold in crab. (Can be made 1 day ahead. Cover and refrigerate.) When ready to bake, place hollowed bread on a rimmed baking sheet lined with parchment paper. Fill bread with crab mixture and sprinkle top with remaining ¼ cup of fontina and ¼ cup of parmesan. Place bread cubes around the loaf and drizzle them with olive oil and season with salt and pepper. Bake in preheated oven for 15-20 minutes until dip is heated through and bread has browned. Garnish with sliced green onions.