Preheat your oven to 350 F (180 C). Place the butter into an 8-inch pie tin or brownie tin and put it into the oven for 5 minutes - just so the butter melts. Swirl the melted butter around in the tin to grease it and then pour the butter into a medium bowl.
To the bowl of melted butter, add the sugar, syrup, salt, egg, vanilla and banana. Beat the ingredients together and add the baking soda, flour, coconut and pecans. Fold in until evenly combined.
Pour the mixture into the greased tin and spread out in an even layer. Sprinkle with the chocolate chips and bake for 25-30 minutes until golden brown. Leave to cool for 5 minutes in the tin before slicing/scooping and serving.