Melt the butter in a saucepan, add onions and watercress and cover with a lid. Cook gently without colour for 5 minutes.
Add the chicken bouillon, bring to the boil, add the potatoes, season with salt and pepper and simmer gently for 30 minutes.
Add the condensed milk and puree in blender until velvety smooth.
Serve with crispy bread croutons.
Preparation: 5 mins
Cooking: 30 mins
4 medium sized Rooster Potatoes
1 small onion (thinly sliced)
1.5ltr chicken stock
250ml unsweetened condensed milk