Chop cauliflower into florets and place on a baking sheet. Coat with 1 Tbsp. olive oil, salt, pepper and red pepper flakes. Roast in a 400 degree oven for about 20 min., or until golden brown. Heat remaining oil in a heavy pot over medium heat. Add leeks and potatoes, season generously with salt and pepper and allow vegetables to sweat/soften for at least 10 to 15 min. Add roasted cauliflower and to the pot and allow wine to reduce until it’s almost gone. Add broth and bring to a soft boil. Stir in seasoning option and allow the soup to cook until potatoes are tender. Remove from heat and use blender or immersion blender to puree the soup completely. When blended, add ½ cup heavy cream (if using) and stir to incorporate. Adjust seasoning here if needed.
Serve with a drizzle of heavy cream or a dollop of sour cream or yogurt and a handful of chopped cilantro or parsley.