Heat the olive oil in a saucepan until shimmering, then add the onion and garlic and sauté until the onion is transparent, without burning the garlic. Add the cream, milk and stock, bring to the boil and then add the peas and gently simmer for 10 minutes. Transfer the soup to a blender and process until smooth. Pass through a sieve and season with salt and white pepper. Pour into 6 bowls and garnish with a swirl of truffle oil. Simon says ‘Shimmering’ means the oil is heated to a point where the surface begins to ripple but does not smoke.