Heat oven to 190C/fan 170C, and spray with oil a baking sheet.
Beat the coconut oil with the sugar, agave, salt and orange zest and mix until light and creamy.
Stir in the flour and mix together to form a dough.
Divide the mixture into 30 tiny balls, or your preferred size, and arrange on a baking sheet covered with parchment paper.
Press each ball flat with the tip of a round-bladed knife.
Chill for 15 mins, then bake for 12-15 mins until light golden and cooked through.
Leave on the baking sheet for 2 mins before releasing with a palette knife. Slide onto a rack to cool.
For the glaze: Melt chocolate and coconut oil in a heat-proof bowl set over a saucepan filled with simmering water, stirring until smooth. Remove from the heat, and stir in sugar
Decorate the shortbread cookies with the chocolate glaze and decorate with chili flakes if desired. Allow to cool and set, then serve.