Add about 6 cups of cooked and peeled chestnuts into a saucepan along with 1 cup of sugar and 1 ¾ cup of water then bring to a boil. Next, let the mix simmer for about 30 minutes on low heat. After that take the pan off the heat and transfer the chestnuts into a food processor while keeping the liquid aside. In a blender, purée the chestnuts until smooth then gradually add the reserved liquid while you keep blending until you reach the desired consistency.