Start by peeling the Yukon Gold potatoes and cutting them into equal-sized chunks to ensure even cooking.
Place the potatoes in a large pot and cover them with cold water. Add a pinch of salt and bring the water to a boil. Lower the heat to a simmer and cook until the potatoes are tender, usually taking about 20 minutes.
While the potatoes are cooking, combine the butter, heavy cream, and sour cream in a small saucepan. Heat over low until the butter melts.
Drain the potatoes well once they are cooked to avoid any leftover water. Then, mash the potatoes to the desired consistency using a potato ricer or stand mixer.
Gradually add the warm dairy mixture to the potatoes, stirring well to combine, you may not use all of it!
Season with salt and pepper, and stir until well combined. Finally, garnish with chopped chives and serve hot.