Soak the chickpeas overnight in water with added salt and baking soda.

The next day, boil them with 1 quart of water until they soften. Drain and set aside.

Finely chop the leeks and garlic, and grate the potato.

In a pot, heat the oil with the butter and add the chopped garlic. Be careful not to let it brown, then add the leeks and grated potato. Stir continuously until they soften and sweeten. Add the chickpeas to the pot. Stir and let them cook on low heat for 5 minutes.

Next, add 2 1/2 cups of the 3 1/3 cups boiling water in which the bouillon cubes have been dissolved. Taste and season with salt and pepper as desired. Let simmer for about 40 more minutes until the leeks are meltingly soft. If more liquid is needed, add from the broth. If you want it thicker, blend some of the chickpeas and add them back to the soup.

Shortly before serving, add the grated cheese to the soup, and if you want it thinner, add the remaining broth. Serve with a tablespoon of raw olive oil on top.