Bring a large pan of salted water to the boil. Strip the kale from the stems and add to the boiling water along with the peeled clove of garlic and cook for about 5 mins until tender.
Use a slotted spoon to remove the kale and garlic and add to a blender. Add the walnuts, juice of the lemon, 2 tbsp of olive oil and a large pinch of salt and whizz until not quite smooth.
Bring the water in the pan back to a boil, add the pasta and cook until al dente.
Drain the pasta, saving a mug of pasta water, then return to the pan along with the kale pesto.
Mix well, adding a little pasta water to get a nice creamy consistency. Plate up the pasta, top with a spoon of ricotta, a pinch of chilli flakes and a drizzle of olive oil.
