Put oven rack in middle position and preheat oven to 400°F. Pour cream into a 9-inch pie plate or shallow gratin dish and spoon lingonberry sauce into cream in dollops (it will be sparse). Put egg whites and salt in a bowl, then set bowl in a larger bowl of hot water and stir whites to warm to room temperature, 1 to 2 minutes. Remove from hot water. Beat whites with an electric mixer at high speed until they just form soft peaks, then beat in granulated sugar, 1 tablespoon at a time, beating until whites just form stiff, glossy peaks. Sprinkle flour over meringue and fold in gently but thoroughly. Whisk together egg yolks and vanilla in a small bowl, then fold into whites gently but thoroughly. Spoon large dollops of meringue onto cream mixture and bake until golden brown and set, 13 to 15 minutes. If you prefer a less creamy souffle, bake 5 minutes more. Dust lightly with confectioners sugar and cool 5 minutes before serving.