To make the cookies, in a bowl, combine All Purpose Flour Blend, baking powder, salt, and confectioners sugar.
Using a hand mixer, stand mixer, or mixing bowl with a wooden spoon - beat the coconut oil until soft and fluffy, about one minute.
With the mixer on low speed, add the granulated sugar until combined. Add the egg and vanilla and mix well.
Add the dry ingredients and mix until a dough forms.
Split the dough in half. Form into discs about 1 inch high, then wrap them in parchment or wax paper. Refrigerate for at least an hour.
Preheat your oven to 360°F. Line a baking tray with parchment paper.
Lightly dust your counter and rolling pin with All Purpose Flour Blend. Roll the chilled dough to 1/8 inch thickness.
Cut using your shamrock-shaped cutters. Place the cookies on the baking tray. Bake for 8 - 10 minutes. Turn the tray halfway through the baking process to ensure an even bake.
While the cookies are cooling, make the icing. Mix the vanilla and half of the milk into a shallow bowl. Whisk-in confectioners sugar until a thick, syrupy consistency is formed. If the mixture gets too thick, add more milk.
To create the marbled-effect, place 8 -10 drops of green food coloring in different areas of the bowl. Drag a toothpick through the icing, pulling and swirling the color around until you have a marble effect. (See our instructional video in the link above under "Special Equipment.")
Carefully dip the cookies top-side down into the icing, and pull straight out. Allow the excess icing to drip before placing the cookie on a wire rack to dry and set.
Repeat until all the cookies are decorated. Add more food coloring to the icing as needed, repeating the marbling process with the toothpick.
Once the icing is dry, serve or store in an airtight container. Happy St. Patrick's Day!