In a large pot cover potatoes with cold water by 1-inch. Add garlic salt and bring to a boil over high heat. Lower temperature and simmer until tender.
While potatoes are simmering, pour buttermilk in a saucepan and add butter. Bring to a simmer. Add chives and alfredo sauce mix. Remove from heat and set aside.
Drain potatoes and return to the pot. Using a potato masher coarsely mash the potatoes until smooth. Slowly add the buttermilk mixture and mix until creamy. Season with salt and pepper, to taste.