On a stovetop, melt the butter in a large pot on a medium to high heat.
Once melted, remove from the heat and add the oats, coconut, sugar, syrup, cocoa powder, chopped nuts, and chopped chocolate. Then sift in the salt, flour, and baking powder.
Using a wooden spoon (or your hands if you don't mind getting them a little dirty), mix the ingredients until they are completely combined, and the color is even throughout.
Place parchment paper in your baking tray, and grease the top of the paper with some butter.
Empty the mixture into your baking tray, and flatten it down with a spoon or spatula, ensuring it's evenly spread (you can apply a fair amount of pressure to make it knit nicely together).
Place the tray in the center of your oven, and bake at 180° C or 360° F for 20 minutes (until just golden on top).