Heat the olive oil in a large casserole dish over a medium heat. Sweat the onion and garlic for 4-5 minutes, stirring occasionally, then add the diced potato. Cover and cook for for 10 minutes until soft, stirring occasionally.
Add the milk, stock, canned chickpeas and bay leaf. Bring to the boil then reduce to a simmer for 20-25 minutes until the chickpeas are soft.
Remove from the heat when the chickpeas are soft and purée the soup. Pass it through a fine sieve into a clean saucepan. Add the extra-virgin olive oil and adjust the seasoning to taste. Ladle into serving bowls and garnish with the chopped dill before serving.