Peel the potatoes, and cut into smaller pieces. Put them in the water in a large pan, and boil them for 10-15 minutes until they are soft.
In the meantime: Chop the onion finely and fry in oil in a frying pan.
Once the potatoes are done, add the onion and bouillon cube, together with the kale. Let it simmer for 5 minutes, then add the cooking cream and let it simmer another 5 minutes.
Now pour the soup (in two batches) into a blender and blend it smooth. Pour it back into the pan, and add salt and pepper. Add the corn starch, and bring it to a boil. Remove from the stove, and serve it with some grated parmesan cheese!