Heat the olive oil in a saucepan over medium heat. Add the diced onion and cook for 5 minutes until soft.
Add the garlic and sage leaves (keep 4 leaves whole for garnish). Cook for 1 minute until fragrant.
Stir in the pumpkin puree, vegetable stock and nutmeg. Bring to a simmer and cook for 15 minutes.
While the soup simmers, cut the bread into cubes and fry in a little oil until golden to make croutons.
Blend the soup with a stick blender until smooth. Stir in the milk and season to taste.
Serve topped with croutons and the remaining sage leaves, fried crisp in a little oil.