Heat the oven to gas 6, 200°C, fan 180°C. Cut the pumpkin or squash into 3cm slices; remove seeds, saving a few for the garnish. Put pumpkin on a baking tray with the onion wedges, garlic and rosemary, and drizzle with oil.
Bake for 20 minutes, then add the pancetta (keep separate in one corner of the baking tray). Bake for a further 20 minutes until the pumpkin is soft inside and brown around the edges.
Reserve the pancetta and rosemary.
Remove the pumpkin skin, then place flesh in a food processor along with the onions and garlic paste squeezed from each clove. Add the stock and milk. Blend until smooth, adding extra milk if needed. Place in a pan, season and heat to taste, and serve with pancetta, pumpkin seeds and rosemary.
Click here to see all our Halloween recipes.