Sauté shallots and rosemary needles in butter, add flour, sauté briefly and pour in the wine. Add milk and stock while stirring. Cook gently over medium heat for 25 minutes.
Reduce the balsamic vinegar and sugar until syrupy, add coarsely crushed pepper.
Melt the remaining butter and fry the seasoned pieces of liver. Remove and turn in the vinegar caramel.
Briefly puree the soup, strain through a sieve, briefly bring to the boil again. Stir in the whipped cream and season with salt and pepper.