Add the potatoes and a nice pinch of salt to a pot filled with cold water. Bring to a boil and cook until the potatoes are tender and cooked through. Drain in a colander.
Add the buttermilk and butter to a small saucepan and heat over low heat until the butter has melted. Transfer the drained potatoes to a bowl and mash, adding the buttermilk mixture as needed to reach the desired consistency. Add the garlic powder and season with salt and pepper. Fold in the cream cheese, cheddar and chives and mix until well combined and melted. Serve immediately.