Preheat oven to bake at 325 degrees Fahrenheit
Carefully, using a sharp knife, make an incision about 1/8-inch deep through each chestnut shell, just into the flesh of the nut, and work your way almost around its circumference.
Place chestnuts on a baking pan and place them in the oven for 30 minutes or until soft.
While the chestnuts are in the oven, sauté the onions in olive oil in a stock pot until clear. Add in minced garlic and sauté for 30 secs.
Then add in 1 cup of chicken broth and chopped cauliflower the to the onions. Cover and let simmer for 10 minutes.
Once chestnuts are roasted, remove them from the oven and while hot, carefully remove the outer shell and papery skin.
Add the rest of the ingredients, including the freshly roasted chestnuts to the stock pot. Salt and pepper to taste.
Simmer, covered for 30 - 45 minutes.
Use an immersion blender to puree the soup to a thick, creamy consistency. (If you don’t own an immersion blender, you can pour the soup into a blender and puree until creamy.)