Preheat the oven to 350℉ and line a baking sheet with parchment paper.
In a mixing bowl, add peanut butter, mashed banana, maple syrup, and sugar, and vanilla extract. Mix until well combined with a wooden spoon - this mixture will be thick.
In a separate bowl, mix together flour, baking soda, and a pinch of salt. Transfer dry mixture into the bowl with the wet ingredients. Mix with a spoon until just combined and no flour streaks remain. Do not overmix.
Shape cookies into approximately 1-tbsp balls and line them on a baking sheet lined with parchment paper. Use the back of a fork to flatten and create a crisscross pattern.
Place in the oven and bake for 12-15 minutes until the cookies have risen and the surface looks dry. Remove cookies from the oven and let cool completely (about 10-15 minutes). They will firm up as they cool.
Store in an airtight container at room temperature for up to 3 days or in the fridge for up to 10 days.