Heat a large pot over medium heat. Add the olive oil and 1 tablespoon butter, then add onions with the salt and pepper. Stir in the garlic. Cook, stirring often, until softened, about 5 minutes. Add in the chopped cauliflower and vegetable stock, then cover and cook for 20 to 25 minutes until softened. A few times during cooking, use your spoon to press down and break apart or mash the cauliflower.
Transfer all the cauliflower and liquid to a blender and (carefully!) puree until smooth. Make sure you hold a towel over top of the blender while pureeing. Pour the cauliflower mixture back into the post and heat over low heat.
Stir in the milk and remaining butter. Stir in the buffalo wing sauce. Keep it over the heat, stirring occasionally, for 10 minutes or so until the soup is all warm again. Stir in the cheddar until it melts. Taste and season with additional salt and pepper or more wing sauce if you’d like.
Serve the soup immediately and top with cilantro, chives, green onions and blue cheese. Extra wing sauce drizzle if you’d like!