Finely chop the onions.

Heat a bit of olive oil and butter in a cooking pot, and add the onions.

Sauté on low heat for 5 minutes.

Chop the zucchini into small cubes.

Add the zucchini to the onions.

Season with salt, pepper and oregano, and sauté for another 10 minutes.

Add 200 ml water, and cook for half an hour.

Grate the cheese.

Use an immersion blender...

... to finely blend the soup.

Add the cheese and stir until it's completely melted.

Stir in the cream, and bring it back to the boil.

Serve in soup plates.