Place the soft butter, vanilla extract, and powdered sugar in the bowl of the standing mixer, and mix for about 3-4 minutes.
Add aquafaba, egg replacer, and lemon zest, and mix. Scrape down the sides of the bowl.
Combine the flour, cornstarch and baking powder and whisk. Gradually add the flour mixture into the bowl and mix.
The batter will be flaky but will stay together if you squish it in your arm.
Shape the dough into two balls and place each portion onto a piece of plastic wrap. Cover with another plastic wrap and roll out into a disk. Place both disks in the fridge for about 20-30 minutes.
Remove the dough from the fridge and place it on a lightly floured surface. Roll out to 1/4 inch (1/2 cm) thickness.
Using a star-shaped cookie cutter cut 20 cookies.
Heat the stove to 350F (160C). Place them on the baking sheet covered with the parchment paper and bake for 10-12 minutes. The cookies should remain pale on the top.
Add agar agar to 5 tbsp of cold water, stir and set aside.
In a small saucepan, combine remaining water and granulated sugar. Bring to a boil, stirring often.
Remove from heat and add agar mixture and cranberry sauce and let it cool a little.
In a mixer bowl, combine aquafaba, xanthan gum (or cream of tartar) and beat for a few minutes on low speed. Gradually increase the speed and beat on high speed for about 5 minutes.
Turn the speed to medium and carefully add the agar agar and cranberry mixture. Whip until the mixture colour is even (for about 4-5 minutes).
Gently add the marshmallow layer to a cookie and cover with the other cookie on top.
Decorate with white chocolate ganache and sprinkle the edible glitter on top.