Bring a large pot of water to a boil, add salt and boil at medium-high heat.
In the meantime, clean and cut cauliflower into small pieces and set aside.
Once the water has come to a boil, add the chopped potato and let cook for about 10 minutes. Add the cauliflower and continue to cook for another 10 minutes until potato and cauliflower is tender when pierced with a fork. Drain well and pat down cooked potato and cauliflower
In a bowl with an immersion blender, or in a food processor, puree the hot cauliflower and potato. Add sour cream, butter, garlic, chicken broth and milk. Continue to blend until smooth. Transfer to a bowl and stir in salt, pepper, jack cheese and green onions or chives.
Garnish with more green onions or chives, and serve hot with pats of butter. Enjoy!