Vidalia onion soufflé was a fixture at Thanksgiving and Christmas meals when City Grit's Sarah Simmons was growing up in Fayetteville, North Carolina. This version—lighter and airier than the one her mother makes—can be prepared in individual gratin dishes or in one big baking dish. Feel free to use any sweet onion you can get, such as Vidalia, Walla Walla or Oso Sweet.
1 stick unsalted butter, plus more for greasing
4 pounds Vidalia or other sweet onions, thinly sliced
3 tablespoons all-purpose flour
2 teaspoons baking powder
6 (large) eggs
2 cups heavy cream
3/4 cup Parmigiano-Reggiano cheese, freshly grated
How to Make It
In a very large skillet, melt the stick of butter over moderately low heat. Add the sliced onions and a generous pinch of salt and cook, stirring occasionally, until the onions are soft and golden, about 40 minutes. Let the onions cool completely.
Preheat the oven to 350° and butter eight 5 1/2-inch gratin dishes (see Note). In a small bowl, whisk the flour with the baking powder and 1 teaspoon of salt. In a large bowl, beat the eggs with the heavy cream and grated cheese. Whisk in the dry ingredients until incorporated, then fold in the onions. Spoon the soufflé mixture into the prepared gratin dishes and bake for about 20 minutes, until the soufflés are set and golden on top. Serve right away.
The soufflé mixture can also be baked in a buttered 9-by-13-inch glass or ceramic baking dish for 45 minutes.