Tip:There are a few secrets to a perfect soufflé: You need to make sure your
oven is properly preheated, the eggs must be at room temperature, you
must not skimp in beating the ingredients (you want as much air in the
mix as possible before the soufflé starts to puff in the oven), and you
must not open the oven door as the soufflé bakes.
Fill a medium saucepan about halfway with water and bring it to a boil over high heat. Stir in the quinoa, reduce the heat to low, and cook until the grains have developed their halos and are tender, about 12 minutes. Drain in a fine-mesh sieve or a lined colander set in the sink. Cool the grains down under some running tap water. Drain thoroughly.
Position the rack in the center of the oven and preheat to 375°F. Lightly grease a 2-quart soufflé dish or round high-sided baking dish with a little butter on a wadded-up paper towel or piece of wax paper, making sure to get the butter down into the seam between the bottom and the sides. Coat the sides and bottom of the dish with the grated Parmigiano-Reggiano, turning the dish this way and that to make sure it’s all nicely cheesed up.
Whisk the egg yolks in a small bowl until creamy and light.
Melt the butter in a large saucepan set over medium heat. Whisk in the flour. Cook for 30 seconds, whisking constantly.
Whisk in the milk in a slow, steady stream; then whisk in the wine, not as slowly, but certainly not all at once, in a heavier but controlled stream. Continue cooking, whisking almost the whole time, until thick and very creamy, about 2 minutes.
Remove the pan from the heat and whisk in the cooked quinoa, beaten egg yolks, pumpkin puree, nutmeg, sage, salt, and pepper.
Use an electric mixer at high speed to beat the egg whites in a large bowl until they form droopy peaks when the turned-off beaters are dipped back in the mix. Use a flat, rubber spatula to fold half these beaten egg whites into the pumpkin mixture until no trace of white remains. Then fold in the remaining half very gently, stirring in wide arcs, until incorporated and even throughout but not dissolved. Scrape, pour, and spread this mixture into the prepared soufflé dish.
Bake until puffed and set, about 40 minutes. Bring it straight to the table and serve it up hot before it begins to deflate.
Save time: Use 1-3/4 cups cooked quinoa and omit soaking and cooking the raw grains.