Preheat oven to 200°C/fan 180°C/gas mark 6.
Place butter, caster sugar and Fate Low Protein All-Purpose Mix Into a mixing bowl.
Mix and knead mixture until it binds together (add water as needed to form a manageable dough).
Transfer to a surface lightly dusted with Fate Low Protein All-Purpose Mix and continue to knead until smooth.
Roll dough to a thickness of 0.5cm, cut out 4 circles with the 3.5cm cookie cutter, 4 circles with the 4cm cookie cutter and 4 circles with the 4.5cm cookie cutter and place onto a lightly greased baking tray.
Cook for 20-25 mins, until golden in colour.
Remove from the oven and cool on wire rack.
Meanwhile, add the green food colouring to the Betty crocker vanilla buttercream style icing and mix well.
Add to the piping bag and pipe a ring of icing onto the largest sized shortbread and place the middle-sized shortbread on top.
Pipe another ring of icing onto the middle-sized shortbread and place the smallest sized shortbread on top.
Pipe a peak onto the smallest sized shortbread and place a star sprinkle at the top.
Top Tip: add ground cinnamon or nutmeg to the shortbread mixture for a Christmassy flavour.
Fate Low Protein All-Purpose Mix is a food for special medical purposes and must be used under medical supervision. This recipe has been specifically designed for a low protein diet.
Refer to labels for allergen and other product information.