Because I am a self 'crowned cook' I don't measure things when I cook and this was my first take at this so you may have to tweak this a little!
1 chicken breast, 1/2 chopped onion, fry light, 1 chicken stock cube dissolved in 1l boiling water, 2 tbsp 0% greek yogurt, 1/2 tub of quark
Fry onion in fry lite but do not let brown.
Add chopped breast and fry until sealed (care not to brown)
Pour in the stock and simmer until liquid is reduced and the chicken is cooked ( you should be able to break the chicken if you press it to the side of the pan with the cooking stick)
Let cool, then blitz until smooth. Add the yogurt and quark (you might try extra light philly, it might make it creamier!) and mix until smooth. (if you know of any 2% cream you can add it in, but I suppose thats dreaming!)
Enjoy!
PS if you store this soup be careful when you warm it, if you boil the yogurt will separate and it will look, well very unappetising!