Heat the olive oil in a large saucepan over a medium heat and sweat the onions with some salt for 6-7 minutes until they start to soften. Add the pumpkin and continue to cook for 10 minutes, stirring occasionally. Add the stock to the saucepan, bring to the boil, then reduce the heat and simmer for 10-15 minutes until the pumpkin is soft.
Purée the soup with a stick blender until smooth. Adjust the seasoning and then ladle into serving bowls. Place the spinach leaves in the centre of the bowls, making sure you submerge them so that they wilt. Serve immediately.
Freezing and defrosting guidelines
Make the soup, then leave to cool at room temperature. Freeze (without garnishes or toppings) in a rigid container, leaving a bit of space for expansion, for up to 1-3 months. Reheat either from frozen or defrost in the fridge overnight. Once piping hot, add toppings or garnishes and serve.