Chop the onions and fry in some olive oil until soft. Peel the pumpkin and remove the seeds and dice. Once the onions are cooked add in the pumpkin and fry for a few minutes. Then add the stock cubes and pour over boiling water until half the mixture is covered. Bring to the boil and simmer until the pumpkin is soft. Add the milk and a pinch of freshly ground black pepper. Blend until smooth.
Then taste and add additional pepper (or salt) if needed.