To make the pesto, place all the ingredients in a small food processor and blitz to create a coarse texture. You can make a larger batch of the pesto by simply multiplying the ingredients; the pesto will keep in the fridge for up to 5 days.
Tip the butterbeans into a large mixing bowl, add in the pesto and combine so that the beans are totally covered. Now add in the spinach and radishes and combine.