Heat the oil in a large pot over medium heat. Add the onions and salt. Cook until translucent and soft, about 8 minutes. Stir in the garlic and cook for another 2 to 3 minutes until fragrant.

Add the beans, broth, and rosemary. Bring to a boil. Reduce the heat to medium-low and cook at a low simmer, uncovered, for about 10 minutes. Stir in kale and lemon juice; the lemon should add a bright note to the soup, so add another tablespoon if you think it needs it.

While soup is simmering, cut the tops off the bread bowls and set aside. Using your fingers or a sharp knife, remove the inner part of the bread bowl, leaving about 1/4-inch thickness all the way around.

Remove the pot from the heat. Use an immersion blender or carefully transfer soup in batches from the pot to a blender. Blend until smooth, about 20 seconds. Blend longer for a completely smooth result or less for a chunkier texture. If using a blender, fill only canister only halfway and remove the knob in the center of the lid and cover with a dish towel; Hot soup creates steam which can cause the lid of pop off during blending.

Taste the soup and adjust with more salt, if necessary. Pour or ladle soup into bread bowls drizzle with a little olive oil. Serve immediately with the bread top placed over the soup or on the side.