Preheat your oven to 180°C/ Fan 160°C/ Gas 5. Peel and chop the pumpkin, drizzle with a little oil, and mix with 10 sage leaves, garlic cloves, salt and black pepper and 150g of the butter, and tip into a shallow roasting tin. Cover tightly with a double layer of foil and place in the oven to roast for 45 minutes.
After the pumpkin has softened, remove the foil being careful of the escaping steam, and remove the sage and crushed garlic cloves. Dice 100g of cold butter and in a food processor blend with the roasted pumpkin to emulsify. Pour in the double cream and check the seasoning. Keep warm.
At the restaurant we brine the scallops in salted pumpkin juice, but at home it is fine to pat the scallops dry and season well with flaky salt.
Heat a small frying pan until smoking and add a little rapeseed oil. Sear the scallops on one side for two minutes, without moving them, until a golden, caramelised bottom is achieved. Turn the heat off as there is enough residual heat left to finish cooking the scallops. Add the remaining 50g of butter to deglaze the pan and turn the scallops over. Add the pumpkin seeds and last four sage leaves to the bubbling brown butter to crisp, spooning the butter over the leaves and scallops.
To plate, spoon some of the pumpkin pureé onto a warmed plate and top with a scallop, sage leaf and pumpkin seeds and a little of the nut-brown butter.