For the cream of chestnut soup, cut the skin of the chestnuts crosswise and place on a baking tray. Sprinkle with a little water and place a bowl full of water in the oven. Roast in the preheated oven at 200 °C for about 20 minutes, the shells will split slightly. Peel the chestnuts and cut them into pieces. Finely chop the onion. Heat butter in a pot and lightly caramelize sugar in it. Add the onions and fry well. Deglaze with the Schilcher and let it boil down. Add the chestnuts cut into pieces and pour in the soup. Season with salt and pepper. Cover and simmer on low heat for about 25 minutes.
Puree the cream of maroon soup with a hand blender and stir in the cream. Season to taste with salt and pepper.