Tear the cavolo nero off the stems and into pieces. Bring a pan of water to the boil, add your cavolo nero for four minutes, then drain and immediately run under cold water to preserve the vibrant green colour.
Squeeze most of the water of the cooked cavolo nero and add to a blender, along with two tablespoons of olive oil, the creme fraiche, basil, parmesan, and a couple of tablespoons of water. Blend together, adding another splash of water if it needs loosening up.
Peel and dice the onion, and peel and finely slice the garlic cloves.
Heat your remaining tablespoon of olive oil in a large pan. Add the onion and garlic and cook for a few minutes until they turn soft and translucent, stirring often.
Drain your butter beans and add to the pan, then add your blended cavolo nero mix. Stir everything together.
Add your stock as well (you can use it to rinse out your blender if needed), stir everything together and allow it all to simmer uncovered for ten minutes, or until starting to thicken up.
Once thickened, season to taste and divide between two - delicious on toast
