Melt butter over low heat.
Sift icing sugar and cornflour into mixing bowl, then add sugar.
Add butter and vanilla essence until thick and creamy.
Press mixture over base of greased 19cm × 29cm rectangular slice pan, smooth with spatula, mark into squares or rectangles, prick lightly with fork.
Bake in moderate oven about 25 minutes or light golden.
Cut into fingers whilst warm and then cool down in tin.