Zucchini and Sweet Potato Soup

zucchini cut into small chunks

olive oil

small shallot (chopped)

garlic clove (grated or finely chopped)

small sweet potato (peeled and cut into small chunks)

bay leaf

raw cashew nuts

vegetable stock (plus more if need to thin the soup)

fresh basil, chopped

Salt and pepper

Basil oil for garnish (optional)