Preheat your oven to 350°F and line a baking sheet with parchment paper.
In a medium bowl, mash the ripe banana until smooth.
Add the peanut butter and mix until the ingredients are fully combined.
Scoop small portions of the cookie dough onto the prepared baking sheet.
Gently flatten each cookie with the back of a spoon or fork. These cookies will not spread much while baking.
Bake at 350°F for 12 to 15 minutes, or until the cookies are set and lightly golden around the edges.
Remove the cookies from the oven and allow them to cool completely. They will firm up slightly as they cool.
Melt the chocolate chips in a microwave-safe bowl in short intervals, stirring until smooth.
Drizzle the melted chocolate over the cooled cookies. Allow the chocolate to set before serving.