Beat butter, margarine, icing sugar and vanilla essence until fluffy and white
Beat in egg whites until combined
Lower speed to low-medium and beat in flour mixture
Divide batter into bowls and add in food coloring. Spoon batter into piping bags/ziplock and snip the corner
Pipe horizontally or vertically on greased cat's tongue pan and bake on preheated 300 F for 20-22 minutes
Cool on rack
Enjoy :)