Place the potatoes in a large pot and cover with water. Bring the potatoes to a boil and cook until tender, about 20 minutes. Drain.
Preheat the oven to 425ºF and adjust the rack to the middle position. Whisk together the yolks, garlic, heavy cream, sour cream, butter and sea salt in a large bowl. Pass the potatoes through a ricer or food mill directly into the egg mixture. Gently stir until combined (don’t over mix). Pour the potatoes into a 3-quart baking dish and decoratively shingle or swirl surface. Bake 30-40 minutes until golden brown on top and slightly puffed. Serve.