Prepare the ingredients: dice the onion, finely chop the garlic, chop the rosemary very finely (2 twigs, leave the 3rd twig whole). Peel the potatoes and cut into 1/2 inch / 1.5 cm cubes.
Heat 1 tablespoon of oil in a large pot, add the chopped onion and rosemary, cook over low heat for 9 minutes until the onion is soft and translucent, but not browned. Add the garlic and cook for a minute fragrant (be careful not to burn it). Transfer everything to a plate and set aside.
Add 2 tablespoons of oil to the pot and add the potatoes. Cook on high heat for about 2 minutes without stirring (letting the potatoes to brown), then cook for 2 more minutes, stirring from time to time, until the potatoes are lightly browned on all sides.
Add the onion with garlic and rosemary back to the pan, then add the broth and 1 whole twig rosemary. Season the soup lightly with salt, bring to a boil, partially cover with a lid, then cook over low heat for about 10 minutes, until the potatoes are tender.
Add the beans together with all the liquid from the can, cook for another 2 minutes.
Remove the pot from heat, discard the rosemary twig. Season with salt and freshly ground black pepper to taste.
Take 2 cups of soup and puree it with a food processor or a blender, then add it back to the pot. (this step is optional, you can also eat the soup without partially pureeing it).
Enjoy!