Preheat oven to 350 degrees. Line or grease a 9x13 inch pan (lining it with tinfoil or something is best because then you can lift the bars right out of the pan and cut them).
In a large bowl, combine the flour, cocoa powder, and salt. Set aside. In another bowl, beat butter and confectioner sugar until creamy. Beat the butter mixture with the flour mixture until combined.
Press mixture into prepared baking pan and bake for about 15 minutes.
In a medium bowl, mix together condensed milk and bananas until incorporated. Once the crust has baked for 15 minutes, take out and pour the banana mixture over it. Combine the chocolate chips, walnuts and coconut together in a bowl and sprinkle over the top.
Bake for abut 25-30 minutes. Let cool completely, roughly around 10-15 minutes. Then, chill in the fridge for about an hour. To chill quicker, place in the freezer for 25 minutes. These are much better when chilled. After chilled, cut into desired sizes.