Potato Soufflé

Instructions

1. Prepare the potatoes
   Place the potatoes in a large pot and cover with cold water. Add 1 teaspoon salt and bring to a boil. Reduce heat and simmer until potatoes are fork-tender, about 15-20 minutes. Drain thoroughly and return to the hot pot for 1-2 minutes to evaporate excess moisture.
2. Make the potato base
   Pass the hot potatoes through a ricer or food mill into a large bowl (or mash thoroughly until no lumps remain). Stir in the butter until melted, then gradually add the warm milk and cream, stirring continuously. Mix in the egg yolks one at a time, followed by the grated Gruyère, nutmeg, salt, pepper, and chives.
3. Prepare the soufflé dish
   Preheat the oven to 375°F (190°C). Generously butter a 2-quart (2-liter) soufflé dish. Coat the buttered surface with a thin layer of grated Parmesan cheese if desired, tapping out any excess.
4. Whip the egg whites
   In a clean, dry bowl, whip the egg whites with the cream of tartar using an electric mixer until they form stiff, glossy peaks. Be careful not to overwhip.
5. Fold and combine
   Gently fold one-third of the whipped egg whites into the potato mixture to lighten it. Then carefully fold in the remaining whites using a large rubber spatula, maintaining as much air as possible. Work quickly but gently, folding just until no large streaks of egg white remain.
6. Bake the soufflé
   Carefully spoon the mixture into the prepared soufflé dish. The mixture should fill the dish about three-quarters full. Run your thumb around the inside edge of the dish to create a small channel (this helps the soufflé rise evenly). Place in the middle rack of the preheated oven.
7. Finish and serve
   Bake for 30-35 minutes until the soufflé has risen well above the rim and is golden brown on top. The center should be set but still slightly jiggly. Serve immediately, as the soufflé will begin to deflate within minutes.