Place turnips, 1/2 teaspoon of salt and sugar in a saucepan; cover with water. Cover and cook until turnips are tender, about 15-20 minutes; drain well and mash (do not add milk or butter). Set aside.
In another saucepan, melt butter; stir in the flour and remaining salt until smooth.
Add milk; bring to a boil. Cook and stir for 2 minutes. Beat egg yolks in a small bowl; gradually stir in 1/2 cup hot milk mixture. Return all to pan; cook and stir for 1 minute. Stir in turnips; remove from the heat. Beat egg whites until stiff peaks form; fold into batter. Spoon into a greased 11-in. x 7-in. glass baking dish.
Sprinkle with bacon.
Bake, uncovered, at 350° for 30 minutes or until golden brown.
