Majorcan Cauliflower and Leek Soup

I got this recipe from a blogger in Majorca called Immaculada - it uses white bread to thicken the soup rather than potato or flour, which is a very 'Spanish' thing.  Cauliflowers are excellent at this time of year, and the leeks are nearing the end of their season, so are coarse, but very flavourful - best used in soup.  You'll need:
2 large leeks and an onion
1 large cauliflower
3 or 4 cloves of garlic
A thick slice of good quality white bread - crusts removed
4 tablespoons olive oil plus extra to serve
Sweet smoked paprika to serve
a Litre of either veg or chicken stock
So simple to make.  Remove the green tops from the leeks, wash well and slice finely.  Peel and finely chop the onion.  Heat the olive oil in a pan and saute the leek and onion over a gentle heat for 10 minutes.  Whilst this is happening, remove the leaves from the cauli, break into florets and slice the stem thinly.  Add to the leeks and onion, along with the peeled garlic cloves, and allow to sweat, with the lid on, for a good 15 minutes.  Don't let the vegetables brown.  Now, make breadcrumbs from the thick slice of bread - it should be a good inch thick slice. Or just tear it into small chunks if you can't be bothered to get the processor out.  Add to the veg with the hot stock, bring to a boil, then reduce the heat to a simmer for about 20 minutes.  Blend with a hand blender or in a processor.  Taste and adjust the seasoning with salt and plenty of black pepper (or white, if black flecks in a white soup bothers you!).  This soup tastes best served warm rather than hot - garnish each bowl with a good drizzle of your best extra virgin olive oil and a sprinkle of smoked sweet paprika.  Immaculada suggests chives too, but I only had a couple of spring onions - they added a nice fresh crunch.