Add 1 cup of the butter beans to a food processor and pulse to crush—do not puree.
Add the crushed butter beans to a mixing bowl and gently fold in all the other ingredients, except for the remaining butter beans.
Put the whole butter beans in the food processor and puree, adding a little water and olive oil as needed to get a smooth consistency. Mix all together and adjust salt and pepper to taste. Spread on toasted ciabatta and serve garnished with shaved pecorino and pickled sweet onions.