Step 1

Preheat the oven to 425°. Position a rack in the upper third of the oven. Generously butter a large rimmed baking sheet and dust generously with superfine sugar. In a large mixing bowl, using a handheld electric mixer, beat the egg whites until soft peaks form. Beat in the superfine sugar, 1 tablespoon at a time, beating well after each addition, until firm peaks form. In a bowl, whisk the egg yolks until pale yellow. Gently fold the egg yolks into the beaten whites.

Step 2

With the spatula, use half of the egg mixture to form four 5-by-3-inch ovals on the prepared baking sheet. With the back of a spoon, make a 2-inch-long indentation in the center of each oval and fill with 1 tablespoon of the jam. Cover with the remaining egg mixture to enclose the jam.

Step 3

Bake the soufflés for about 10 minutes, until puffed and golden brown but still slightly jiggly in the center. With a metal spatula, gently transfer the omelets to plates. Dust with confectioners' sugar and serve right away.