Start by toasting the desiccated coconut in a large pan. Toast on a medium heat until golden, stirring or flipping continuously. Set aside to cool. Note: Do not leave unattended as it'll start browning very quickly.
Preheat the oven to 175℃/350℉. Line a 23cmx33cm baking pan with cooking spray or a thin layer of butter. Set aside.
To a large bowl, add the 1 cup softened butter, sugar and golden syrup together. Whisk until fully combined, about 2 minutes.
Add the egg, coconut essence, and buttermilk. Whisk until mostly combined, about 1 minute. Note: the mixture will look like it has split but this is normal.
Add the flour, baking powder, milk powder, toasted dessiccated coconut and salt. Use a spatula to fully combine. The batter will be thick and slightly sticky.
Melt the remaining teaspoon of butter and line the palm of your hands. Add the batter to the baking tin and firmly press the batter into your baking tin, spreading evenly. Bake for 45minutes or until the edges become dark brown a skewer comes out clean. Set aside to cool.
Once the sponge has mostly cooled, you can start sectioning the sponge into rusks using a serrated knife. Note: Aim for 4 rusks lengthwise and 7 rusks width wise (this is a personal preference but you can slice them thicker or thinner - it's up to you). The thicker they are the longer they will take to dry.
Drying: Preheat the oven to 100℃/212℉. Lay the sectioned sponge out onto a baking tray that's been lined with a rack, ensuring the tray isn't overcrowded. Place in the oven, with the door slightly ajar (using a cloth) ,and dry for 2-6 hours or until fully dried. Note: the rusks must be fully dried otherwise they'll slowly start to soften and stale.
Once they've fully dried. Make yourself a fresh cup of steaming hot coffee and get dunking! Enjoy, tastebud.
