Preheat your oven to 350°F (175°C) and line two baking sheets with silpats or parchment paper.
Sift together the flour, baking powder, baking soda and salt in a medium bowl and set aside. In your stand mixer, cream the margarine and granulated sugar until soft and fully combined. Grind the flax seeds into a powder with a spice grinder, and whiz them together with the water. Add the flax seed mixture to your mixer. Incorporate the vanilla and “sour cream,” scraping down the sides of the bowl as necessary to achieve a completely smooth mixture. Slowly add in the flour mixture, stirring just enough to combine without any lumps remaining.
Onto the prepared baking sheets, drop about ¼ cup of dough for each cookie, leaving plenty of room for them to spread, roughly three inches between each. Lightly moisten your hands to prevent sticking and gently pat the dough mounds into approximately 2½ inch disks. Bake for 14 to 17 minutes, until they just begin to turn slightly golden in color. Let the cookies rest on the baking sheet for 2 additional minutes, and then transfer them to a wire rack to cool completely.
For the vanilla icing, whisk together 1 cup of the confectioner’s sugar in a small bowl with the soy creamer and vanilla, ensuring that you have a completely smooth mixture. Add in the remaining 1 cup of sugar and combine. Even though it may seem too dry at first, continue stirring and it will soon reveal itself as a nice, thick icing. Set aside.
For the chocolate icing, place the chocolate, soy creamer, and corn syrup in a microwave-safe bowl and heat for 30 to 60 seconds, just until the chocolate begins to melt. Stir rapidly and thoroughly to combine all of the ingredients, until the chocolate is completely smooth. Set aside to cool while you continue to work. Starting with the vanilla icing, use a spatula to spread the white glaze on half of each cookie. Let the glaze set for at least 10 minutes.
Returning to your chocolate icing, add in the 1 cup of confectioner’s sugar and stir until completely smooth. Spread on the other half of each cookie. Let the cookies sit until the glaze has fully set up.