Bring a large saucepan of generously salted water to boil and add the kale. Simmer on a medium/low heat for around 10 minutes until you can easily place a fork through the stalks.
Meanwhile, set a Dutch oven or similar pan to a low/medium heat, add olive oil and gently fry the onions until soft
Add the garlic and cook for a further minute
Set your Dutch oven or pan to a medium heat, add the spinach and cook until wilted (note 1)
When the kale is cooked strain with a colander and add to the main pan with the spinach
Pour in the stock and simmer for 5-10 minutes with the lid on
While the soup simmers, place the cottage cheese in a food processor, add 1tbsp water, puree until completely smooth and set aside.
Puree the soup mixture with a hand or countertop blender until completely smooth and return to the main pan (note 2)
Stir in the cottage cheese, parmesan and lemon juice
Add salt and pepper to taste.
Serve in bowls topped with lemon zest.