Preheat the oven to 425°F (218°C)

Cut the onions in half, leaving the root ends intact and peel them. Be sure not to leave any of the tough layers on, it’s okay to peel 2 to 3 layers off.

Brush the onion halves with olive oil, season with salt and pepper and place the flat side down in a large baking pan.

Add the vegetable stock and scatter the bay leaves around the onions. Cover tightly with foil and bake for approximately 1 ½ hours or until the onions are very tender and nicely caramelized.

While the onions are baking, toast the fennel seeds in a small skillet over moderate heat until fragrant. Approximately 3 minutes. Transfer to a work surface and let cool. Use a morter and pestle to coarsely crush the seeds, or you can mince with a sharp knife. Transfer to a small bowl and add the panko breadcrumbs, sage, and the 2 tablespoons of olive oil. Season with salt and toss to combine.

Carefully turn the onions over, flat side up, in the pan and evenly spoon the fennel breadcrumbs on top and bake for about 15 minutes, or until the crumbs are lightly browned on top. Discard the bay leaves and serve hot.