This is a mild, subtle soup whose flavors are tuned to flatter the sweet fruitiness of the chantrelle. If you wish, you can augment the nutmeg with a dash of powdered cumin to add an additional hint of mystery.
Start by peeling the potatoes, cut them into cubes and boil them in salted water for about 20 minutes, until soft. Put them in a blender or food processor, along with the nutmeg and chicken stock, and blend until smooth, thick and creamy.
Clean the chantrelles and chop them into small chunks. Chop the shallots very finely, and combine them with the chantrelles and butter in the bottom a stock pot. Sauté the shallots with the chantrelles on medium heat until the shallots are translucent (about 10 minutes), then add the finely chopped broccoli and the sherry. Cook for an additional 3 minutes on higher heat, stirring.
Now add the puréed potato mixture, along with 1 cup of milk. Stir to heat evenly, but avoid boiling. Remove from heat, and ladle onto soup plates. Garnish the top with chopped basil and parsley before serving.