With an electric mixer,beat the softened vegan butter, both sugars and vanilla until creamy. Beat in the aquafaba.
In a separate bowl, mix together the flour, salt, baking soda, baking powder and cream of tartar.
Add flour mixture to batter and stir until very well mixed, then stir in the oats, nuts and chocolate chips.
Using a medium size cookie scoop, shape dough into 24 balls. Cover and chill for an hour or until ready to use (if you can wait a day, the cookies bake up even nicer with dough that's been chilled 24 hours).
Preheat oven to 350 degrees F. Arrange cookie dough pieces on a parchment or foil lined baking sheet spacing about 3 inches apart. Bake 10-12 minutes (these are better underbaked than over!) or until golden brown around the edges.
As soon as the cookies come out of the oven, set reserved Oreo pieces on hot cookie, crème side down to they will adhere. If the cookies have spread during baking, gently push edges inward with inverted tip of a spatula.
Let cool until firm enough to remove from baking sheet.