Rinse the dried white beans thoroughly under cold water, removing any debris or damaged beans, then set aside.
Chop the yellow onion finely and mince the garlic cloves, releasing their aromatic fragrance.
Add the rinsed beans to the slow cooker along with the vegetable broth, chopped onion, minced garlic, dried thyme, and bay leaves. Stir gently to combine.
Cover the slow cooker with the lid and set it to low for 8 hours or high for 4-5 hours, until the beans are tender and starting to fall apart.
Once cooked, remove the bay leaves and use an immersion blender to blend part of the soup directly in the pot, creating a creamy, slightly chunky texture.
Stir in the olive oil, season with salt and pepper to taste, and add a squeeze of fresh lemon juice to brighten the flavors.
Ladle the hot soup into bowls, drizzle with a little extra olive oil if desired, and serve immediately, garnished with fresh herbs or crusty bread.