Prep Potatoes. Peel the potatoes and cut them into 1 inch cubes. Soak potato cubes in water for 15 minutes to remove excess starch, then strain them.
Boil Potatoes. Place them in a large stock pot and fill it with enough water to barely cover the potatoes. Place the lid on and bring to a boil. Once boiling, lower to a simmer and simmer for 15 minutes (or until fork tender).
Make Butter Sauce. When potatoes are about finished make the butter sauce. On low heat in a medium saucepan, melt butter slowly. Then, stir in sour cream and cream cheese. Once melted, add in heavy cream. Don't allow it to boil.
Mash the Potatoes. Strain off potatoes and return them to the hot stock pot (with heat turned off). Allow them to sit for 5 minutes to steam off any excess water. Then, mash the potatoes.
Flavor the Potatoes. While still in the stock pot, stir in nutmeg, onion powder, salt and pepper. Lastly, mix in the butter cream sauce.
Serving. Serve immediately or allow it to cool and transfer it to an airtight container to save for later. Serve with slices of butter and chives.
Notes
Storage
These mashed potatoes can be refrigerated for up to 4 days, but we find they are best if used within 2 days.Freezing the potatoes will change the texture when reheating so I don't recommend it, but if you choose to, they will keep for up to 3 months in an airtight container.To reheat, place them in a baking dish and bake them at 325°F for 15 minutes or until completely warmed through.
Make-Ahead Option
I like to store these potatoes in a baking dish. Pour the mashed potatoes into a baking dish and press plastic wrap directly on top so moisture can't escape. This will keep them from drying out. Then, store in the fridge for up to 2 days.