Heat the olive oil in a small saucepan over a medium heat. Add the onions and gently fry for three minutes, until softened.
Add the peas and stock, bring to the boil, then reduce the heat to simmer for 10 minutes.
Add the double cream, salt and pepper and heat through for one minute. Pour into a food processor and blend until smooth.
To serve, pour into a bowl and garnish with a swirl of double cream and a sprig of mint.