In a large saucepan, heat 2 tablespoons of olive oil over medium heat. Add 1 chopped onion and 1 thinly sliced fennel bulb, stirring frequently. Sauté for about 5-7 minutes, or until the onion is translucent and the fennel is softened.

Pour in 4 cups of reduced-sodium chicken or vegetable broth, followed by 2 cans of rinsed and drained cannellini beans, and 1 can of diced tomatoes. Sprinkle in 1 teaspoon of dried thyme and freshly ground black pepper to taste. Add 1 bay leaf and stir everything well.

Increase the heat to high and bring the soup mixture to a rolling boil, which should take about 5 minutes.

Reduce the heat to low, cover the saucepan, and let the soup simmer for 30 minutes.

After 30 minutes, remove and discard the bay leaf from the soup. Stir in 2 cups of shredded fresh spinach and cook for an additional 3-4 minutes until the spinach has wilted.

Ladle the soup into bowls while it’s still warm. Consider topping each serving with freshly grated Parmesan cheese or a sprinkle of chili flakes.