Preheat the oven to 350°F. Line a cookie sheet with parchment paper.
In a large bowl, stir together the banana, peanut butter, honey, stevia, vanilla, and water.
To the banana and peanut butter mixture add the oats, baking powder, and cocoa powder.
Stir the oat mixture into the banana mixture until combined.
Using a cookie scooper, drop mounds of dough 2 inches apart on the prepared cookie sheets. Using your hands, flatten, and spread each mound of dough shaped like a cookie.
Place in the preheated oven and bake for 13 to 15 minutes. Remove from oven and allow cookies to cool down.