Put the squash and sweet potatoes, with their skins, onto a baking tray and sprinkle with a dribble of olive oil and sea salt. Roast for around 25 minutes, a skewer inserted into the flesh should go right through with ease. Remove from the oven and cool to the point at which you can remove the skin.
Meanwhile, place the halved salad onions on the baking tray with a dribble more oil and roast for about 15 minutes until browned and softened, turning them over at half time.Put a small frying pan on the heat and when it is hot, throw in the pumpkin seeds and toast them for around a couple of minutes until they pop, stirring to turn them, and not allowing them to blacken. Remove to a plate. Put a dessert-spoon of olive oil in the pan, heat until hot and throw in the sage leaves until they crisp and frizzle, about a minute. Remove to a plate. Assemble the salad beginning with the squash and sweet potato. It looks good on a large, warm, white plate. Strew the onions over the squash and then tear the milky burrata with your hands and scatter it on the plate. Scatter the pumpkin seeds and sage leaves on top, dribble over a little more grassy, peppery olive oil and season to taste.