Cream together the room temperature butter and peanut butter at medium speed.
Beat in the sugars, stopping to scrape down the sides as necessary.
Add aquafaba (or milk) and vanilla - blend to incorporate.
Add the baking soda, salt, and flour. Mix on low-medium speed just until incorporated.
The dough will be thick (moist crumbles). Give a final stir with a rubber spatula or a mix with hands to incorporate. If the dough is too sticky/soft, add an additional tablespoon of flour. Using a trigger scoop or tablespoon, measure out 16-18 balls of dough around 1 ½ tablespoons each (drop onto cookie sheet and press with fork or) roll with hands into a ball.
Arrange 2" apart on parchment lined baking sheet. Using the back of a fork, gently press a criss cross pattern into each cookie.
Scatter and press a few sprinkles onto the cookie (optional topping).
Bake right away or place the baking sheet into the fridge for 30 minutes - 2 hours to chill the dough for thicker cookies.