Tuscan bean soup

Tuscan bean soup
This soup, ribollita, is thick, filling, nutritious, and delicious. It is even wonderful
at room temperature.

1⁄4 cup extra virgin olive oil, plus more for serving
1 onion, chopped
2 carrots, sliced
1 leek, white and pale green parts only, sliced
2 garlic cloves, chopped
1 quart (1 liter) chicken stock
one 14.5oz (411g) can chopped tomatoes
1 tbsp tomato paste
one 15oz (420g) can white kidney (cannellini) beans, drained and rinsed
9oz (250g) spinach, sliced
salt and freshly ground black pepper
8 slices Italian bread
2 tbsp grated Parmesan (optional), for serving
Heat the oil in a soup pot over medium-low heat. Add the onion, carrots, and leek and cook
until softened but not colored. Add the garlic and cook for 1 minute. Add the stock, tomatoes and their juices, and tomato paste. In a bowl, mash half the beans with a fork and stir into the pot. Bring to a boil over high heat.
Return the heat to medium-low and simmer for 30 minutes. Add the remaining beans and spinach and simmer for 30 minutes more.Place a slice of bread in each soup bowl. Ladle in the soup, and, if you like, top with a sprinklingof Parmesan.  Good with a dollop of pesto placed on top and olive oil passed on the side.
Prepare ahead this soup is best made ahead and reheated.