
Cook the potatoes:
Place your potatoes in a large pot. Cover with cold water and season liberally with salt. Bring the water up to a boil. Cover the pot and cook the potatoes skin-on for about 20 minutes or until tender. The potatoes are done once they easily slide off when pierced with a sharp paring knife. Drain the potatoes and peel using a sharp paring knife while still hot. Press the warm potatoes through your potato ricer or pass them through a tamis to get a smooth puree.
Assemble your puree:
Heat the heavy cream until just below a light simmer. Add nutmeg to taste to the heavy cream and mix well.
Incorporate the heavy cream into your puree while stirring constantly with a wooden spoon or spatula until it has reached your desired consistency. Take your cold butter cubes out of the fridge and whisk them into your puree, stirring constantly with a wooden or spatula. Taste the puree for seasoning and add more salt to taste.
Optional:
Pass the finished puree through a fine-mesh sieve or tamis to get an ultra-smooth puree.