Sift flour, sugar, and salt together in a mixing bowl. Pour the milk slowly into the dry mixture while stirring. Add the egg yolks one at a time, beating until well blended before adding the next egg yolk.
Place the egg whites in a separate bowl; beat until egg whites form stiff peaks. Gently stir 1/3 of the egg whites into the batter. Fold in the remaining egg whites.
Melt 1 tablespoon butter in an 8 inch skillet over moderate heat. Pour in half the batter and cook about 4 minutes or until browned on the bottom. Loosen edges and slide pancake onto a plate using spatula. Invert the pancake back into the skillet and cook until both sides are brown, about 2 minutes. Remove to a warm platter and keep warm.
Make the second pancake the same way. Dust with confectioners' sugar and serve.