Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, cornstarch, cocoa powder, cinnamon, and salt until thoroughly blended, ensuring that no cocoa powder lumps remain.
In the bowl of a stand mixer, using the paddle attachment, cream butter and the Redpath® Demerara Style Sugar and Redpath® Granulated Sugar until fluffy and pale in colour; about 3 minutes. Mix in the vanilla extract.
Add the dry ingredients into the bowl. On low speed, stir until just combined. Add in the chopped chocolate, mix on low speed until chocolate is evenly mixed throughout the dough.
Form dough into a flat disc and wrap well in plastic wrap. Place into the fridge to chill and rest; 30 minutes.
Place dough between 2 sheets of parchment paper. Roll to a ¼-inch thickness. With desired cookie cutters, cut out shortbread. Place onto the prepared baking sheet and place into the freezer to chill; at least 15 minutes.
Place chilled cookies into the preheated oven and bake for 7 to 8 minutes, rotating halfway through.
Remove from oven and allow to cool completely on the baking sheet before removing.
In a small bowl, stir together the Redpath® Icing Sugar and pomegranate juice until smooth. Add more juice if a thinner consistency is desired, alternatively add more icing sugar if a thicker glaze is desired.
With a clean pastry brush, brush completely cooled shortbreads with the glaze. Place back onto the cooling rack or a parchment lined baking sheet to allow glaze to set. If desired, drizzle set shortbreads with extra glaze.
*Chop chocolate as fine as possible to ensure clean cuts when using the cookie cutter.
*If a more pronounced red is desired, add a drop of red gel food colouring to the glaze. Alternatively, use pomegranate powder to tint the glaze.
*Cranberry juice can be used in place of the pomegranate juice.
*Shortbread can be baked from frozen; add about 1 to 2 minutes to the baking time.