In the bowl of an electric mixer fitted with a paddle attachment, mix the butter, icing sugar, pure vanilla extract, and orange zest, until creamy.
Add the egg and mix until just incorporated.
Stop the mixer and add the cocoa powder.
Next, add Peetz S.M.A.R.T (Sorghum, Millet, Arrowroot, brown Rice, Tapioca) Blend all at once.
Mix just enough to combine.
Wrap the dough in plastic wrap and let rest in fridge until ready to roll out and use.