Preheat oven to 350 degrees. Spray a 9 inch tart pan with a removable bottom with non-stick cooking spray.

In a large bowl, beat butter, sugar, 1 Tbsp. lime zest and vanilla until fluffy.

In a medium bowl, whisk together baking flour, coconut flour and salt.

Gradually add flour mixture to butter mixture until just combined.

Press the dough into the prepared pan. Poke crust with the tines of a fork about every inch.

Bake for 20 minutes or until golden brown.

Glaze:

In a medium bowl, whisk together all glaze ingredients. Add the glaze to a small Ziploc bag. Cut off a tiny piece at corner bag to pipe the glaze through.

Remove the shortbread from the oven and cut into 8 wedges using a sharp knife. Let cool in pan.

When cool, remove from pan to a wire rack and drizzle with glaze, then sprinkle with toasted coconut and extra lime zest.