1. Place a large pot on the stove over medium heat. Add the butter and then the onions and sweat them down with a pinch of salt for five minutes. You don't want the onions to colour so reduce the heat further if you need to.
2. Add the thinly sliced cauliflower with a bit more salt and saute that with the onions for another 10 minutes on low heat. Give it an occasional stir to make sure it's not browning.
3. Add the stock,thyme and bay leaf and bring to a simmer. Now add the large pieces of cauliflower and allow to simmer for 10 to 15 more minutes,or until the large pieces of cauliflower are tender. When everything is cooked,remove and discard the thyme and bay leaf,and pull out the large pieces of cauliflower and set them aside. Add the cream,if using,to the soup and blend to a smooth puree. Adjust seasoning and consistency with salt and splash of water if you prefer a thinner soup.
4. Chop the large pieces of cauliflower roughly and recombine with the pureed soup. Bring everything back to a simmer.
5. To serve,distribute among four bowls,adding 30g of grated cheese to the top of each bowl. Crack a bit of pepper over that and add a drizzle of good extra virgin olive oil. Serve immediately.
Serving suggestion:Parmesan and thyme monkey bread (pull-apart).
Find more of Danielle Alvarez's recipes in theGood Food Favourite Recipes cookbook.