Line a large baking sheet with parchment paper or wax paper. Keep it handy.
In a small bowl, mash your banana until as smooth as possible. You should have about 1/3 cup, but don't stress if it isn't exact.
In a medium saucepan place the peanut butter, milk, cocoa powder, coconut oil, and salt. Heat over medium, until the peanut butter and coconut oil melt and are easy to whisk. The mixture may look a little gritty at this point, which is fine.
Remove the pot from the heat. Whisk in the honey, banana, and vanilla extract until smooth and most of the banana lumps have disappeared.
Using a rubber spatula or wooden spoon, fold in the oats.
With a cookie scoop or spoon, drop the dough by heaping tablespoons onto the prepared baking sheet. With your fingers, gently flatten tops and press around the sides to form the mounds into a cookie shape. Press the chopped chocolate decoratively on top.
Place the no bake cookies in the refrigerator for 30 minutes to chill. This time is important to allow the oats to soften up and the flavors to meld.
To make your own quick cooking oats: pulse rolled oats in the food processor 3 or 4 times to lightly break them up (do not pulse all the way into a flour). You can also used rolled oats, but I find the cookies do not have as nice of a texture or flavor as they do with quick cooking oats.
Store leftover no bake cookies in the refrigerator for up to 1 week. The banana flavor will become more pronounced as the days go on, but the cookies will still be delicious.
To Make Vegan: Use maple syrup in place of the honey and non-dairy milk.
To Make Gluten Free: Make sure your oats are certified GF.