1. Cut the pumpkin into quarters and remove the seeds. Peel the quarters and cut them into 1-2 cm cubes. You can prepare more than necessary: pumpkin and squash cubes freeze very well.
2. Peel and cut the potatoes into 1-2 cm cubes. Peel and roughly chop the onions. Remove the dark green part of the leek. Cut the white part into four lengthwise, then into small pieces. You can tie and freeze the green part. It will flavor a soup or a pot-au-feu.
3. Melt the butter in a pressure cooker or a pot. Sauté the onions and leeks for 5 minutes without letting them brown. Then add the pumpkin and potatoes.
4. Heat the milk and pour it into the pot. Add hot broth or 50 cl of very hot water and 2 bouillon cubes. Do not add salt. Close the pressure cooker and let it cook for 30 minutes (1 hour in a regular pot).
5. The preparation can be served as is (as a soup), passed through a vegetable mill, or finely blended to obtain a smooth soup. Whatever your choice, adjust the seasoning before serving with salt and possibly pepper.
To finish: Serve very hot with a pot of thick cream on the side, which everyone can serve as they wish.