In a small bowl cream butter and sugar; gradually add flour. Press into an Ungreased 8x8 baking dish.
Bake 12 minutes. Cool slightly.
While crust is baking, in small bowl beat eggs, sugar, lemon juice and baking powder until frothy. Pour over warm crust. Bake 15 to 20 minutes or until lightly brown. Cool on wire rack. Dust with confectioners' sugar. Cut while slightly warm.