In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
Remove aquafaba from the refrigerator and whisk until slightly frothy.
With an electric mixer, cream butter and both kinds of sugar together on high speed until the mixture lightens in color and sugar is fully incorporated.
Reduce speed to medium-low and add the aquafaba and vanilla.
Slowly add the flour mixture to the butter mixture, scraping down the sides of the bowl as needed with a rubber spatula.
Stir in the chocolate chips and chopped walnuts.
Chill the cookie dough for fifteen minutes in the freezer, or for at least thirty minutes in the refrigerator.
While the dough is chilling, preheat your oven to 375 degrees.
Line a baking sheet with a silicone baking mat or parchment paper.
After the dough has chilled, use a 1/3 cup** measure to portion large balls of dough on the tray, slightly flattening the top of each one with your hands.
Bake for 18-20 minutes, or until the cookies are slightly browned around the edges.