Preheat the oven to 220°C (430°F). Bring a large pot of water to a boil with a halved Onion, Bay Leaves and a generous pinch of Sea Salt.
Add the Octopus to the simmering water and cook gently until tender, about 40–60 minutes depending on size; test with a fork. Reserve a cup of the cooking liquid, then drain and let the octopus cool slightly.
While the octopus cooks, scrub the New Potatoes and toss them with 3–4 tablespoons of Extra-Virgin Olive Oil, crushed Garlic, a good grind of Black Pepper and a little more sea salt. Spread the potatoes on a roasting tray and roast until golden and tender, about 25–35 minutes, turning once.
Cut the cooled octopus into large pieces and arrange them on the tray with the roasted potatoes. Drizzle generously with more extra-virgin olive oil and spoon a few tablespoons of the reserved cooking liquid over the octopus to keep it moist.
Return the tray to the oven and roast everything together for 10–15 minutes, until the octopus edges begin to char and the oil becomes glossy and infused with garlic.
Remove from the oven, scatter chopped Parsley over the dish, add a final drizzle of olive oil, a pinch of sea salt and a crack of black pepper. Serve hot with crusty bread to soak up the flavorful oil.
