For the cookie dough, with your electric mixer (paddle attachment) cream the vegan butter with the sugar until light & fluffy about 3- 5 minutes.
Add the lemon zest, aquafaba & the extracts to the creaming butter/sugar mixture until incorporated (it will probably look slightly curdled) then stop the mixer & scrape the sides of the bowl then whip it on high speed for 20 seconds to emulsify
Next sift together the flour, baking powder & salt & add it all at once to the creamed mixture. Mix just until it is all combined do not overmix.
Turn the dough out onto a large piece of plastic wrap, bundle it up & chill for at least 1 hour (or up to a week in the refrigerator) before using~ this allows the dough to relax & absorb the flour so it will roll better
When you are ready to cut out your shapes you must re work this dough with some additional flour to a pliable consistency after it has been chilled. Do not skip this step. *see video for visual
Roll the dough to ¼" thick or to your desired thickness & cut shapes as desired
Transfer cookie cutouts to a parchment lined sheet pan & bake in preheated 350℉ oven for approximately 18-22 minutes or until light golden brown. (time depends on thickness & size of cookies)
Cool the cookies while you prepare the vegan royal icing
For the Royal Icing: combine the egg replacer with the warm water & whisk smooth
Place the sifted confectioners sugar in a mixing bowl then add the vanilla extract & the egg replacer mixture.
Whip on medium to high speed until it is smooth
Color as desired with gel paste food colors & decorate!
Allow cookies to dry at room temperature overnight