In a heavy saucepan, heat the low-fat spread.
Add sliced mushrooms and finely chopped onion.
Cook, stirring constantly with a wooden spoon, for 3 minutes.
Add flour to the pan and cook, stirring, for 1 minute.
Remove from heat.
Gradually blend in the vegetable stock, then the milk, sweetcorn.
Return to the heat, bring to a boil, reduce the heat, and simmer the soup gently for 10 minutes, stirring occasionally.
Season the soup with salt and pepper.
Ladle the soup into warm bowls and garnish each serving with a swirl of low-fat single cream.