In a large bowl combine the bread cubes, sugar, and True Lemon.
Drizzle with melted butter and mix until ingredients are well blended.
In a separate bowl, beat yolks with an electric mixer until thick and lemon-colored; then add milk and blend well.
Pour the yolk and milk mixture over the bread mixture.
Meanwhile, in glass bowl, beat whites until stiff peaks form, then fold into the bread mixture.
Pour this mixture into a buttered 1 1/2-quart casserole and bake at 325 degrees for approximately 30-35 minutes.
Allow to cool and dust with powdered sugar before serving.