2) Season with salt and pepper. Run everything through a food mill on a medium dye, over a medium pan. If the mixture is too thick, thin with water to desired consistency. Add milk right before serving.
3) Garnish the soup with croutons and a dollop of yogurt.
For the croutons:
1) Cut the bread into cubes and place into a large bowl; add the chopped garlic and chilli flakes. Season with salt and pepper and toss with olive oil.
2) Transfer to a baking tray and place in the oven for 5 to 7 minutes, until golden brown.
For the yoghurt:
1) Mix the Greek yoghurt with the chopped chives. Season with salt and pepper, to taste.