1 pound dried white cannellini beans OR
4 (15oz) cans cannellini beans, drained and rinsed
4 cups sliced yellow onions (3 onions)
1/4 c good olive oil
2 garlic cloves, minced
1 large branch fresh rosemary (6 to 7 inches) or 1 tsp of dry rosemary
2 quarts vegetable stock
1 bay leaf
1-2 tsp kosher salt
1/2 tsp black pepper
If using dried beans: In a medium bowl, cover the beans with water by at least 1 inch and leave them in the fridge for 6 hours or overnight. Drain.
In a large stockpot over low to medium heat, saute the onions with the olive oil until the onions are translucent, 10 minutes. Add the garlic and cook over low heat for 3 more minutes. Add the drained white beans (or drained cans of beans), rosemary, vegetable stock, and bay leaf. Cover, bring to a boil and simmer for 30 - 40 minutes if using dry beans (until beans are very soft) or 15 - 20 minutes for canned beans. Remove the rosemary branch and the bay leaf.
Pass the soup through the coarsest blade of a food mill, or pulse in food processor until coarsely pureed.
Return to pot and reheat and add salt and pepper, to taste.
I used canned beans because it's easier. I put less salt than it called for because canned beans have salt in them already. I scooped out the dry rosemary with a slotted spoon. I will only puree half of the soup next time and leave some of the onions and beans whole for a chunkier texture.