Preheat the oven to 325 F (170 C).
Mix the quick or rolled oats, desiccated coconut, flour, and brown sugar together in a bowl.
In a separate mixing bowl, mash the banana (or substitute with vegan butter).
Add the wet ingredients (banana, vanilla extract, and dairy-free milk) to the dry ingredients (rolled oats, coconut, flour, sugar, salt, and baking soda) and, using your hands, mix well until you obtain a sticky cookie dough.
OPTIONAL: At this stage add any extra toppings you may wish to use.
Roll the cookie dough into a sausage shape and cut it into 15 thick vegan oatmeal cookies.
Line the cookies onto the tray covered with the prepared baking sheet and bake in the center of the oven for 12 to 14 minutes.
Allow the cookies to cool completely on a cooling rack before enjoying.