This is a very simple soup that can be made quickly with very little effort. It becomes amazing with just a few drops of a flavoured oil added as it is served. I recently bought a small bottle of white truffle flavoured olive oil and a few drops of that, as you might expect, really makes this soup devine.
The key ingredient is white beans. The specific type does not really matter, and even the whiteness is probably optional, except that part of the charm is in the colour. I often use butter beans, but haricot beans are another good option. I generally use dry beans that I soak and cook, but I am sure a ready-to-go tin of beans would be just fine too. This soup tends to appear when I have cooked some beans just a bit too much and they are starting to fall apart.
There are options in the degree of effort you want to invest :
The simplest is to just purée the beans, some of their cooking water and some salt and pepper, serving with a drizzle of flavoured oil.
A nice middle ground between no effort and some effort is to add a bit of stock or garlic to the purée.
And the whole hog involves sweating some aromatic vegetables then adding the beans and stock, puréeing and then passing the mixture through a fine sieve to make the soup even more velvety and smooth.
This is real frugal food with great pay off in nutritional value, percieved effort and depending on the flavouring used, variety!