Mash bananas first, add the quick oats, and mix them together using a spoon or spatula until blended.
Add the chopped walnuts and other mix-ins.
Place the mixture in 12 rounded scoops on a cookie sheet (greased or use parchment paper or non-stick foil). Flatten each mound and bake at 350° for about 15 minutes.
Lightly press toasted oatmeal onto the top of the cookies to finish.