Preheat a camp oven to 350 degrees F (180 degrees C). Fully line, including the sides, a slice tray, or an 11- by 7-inch (28cm x 18cm) cake tray.
Slice Base
Combine the flour, brown sugar, desiccated coconut, and salted butter in a bowl until well mixed.
Transfer to the lined slice tray and press down to create the base layer.
Bake for 10 minutes until lightly golden, then remove from the oven. Leave in the slice tray to cool.
Caramel Filling
Combine the condensed milk, golden syrup, and butter in a saucepan over medium heat. Whisk continually while heating for 8 minutes or until golden.
Pour the condensed milk caramel over the cookie base. Return the tray to the oven and bake for 8 minutes.
Remove from the oven and leave in the tray to cool. When at room temperature chill for 3 hours or until fully set.
Chocolate Topping
Place the chocolate and vegetable shortening into a heatproof bowl over a pot with a small amount of water. Slowly heat while stirring, until all the chocolate is melted.
To Assemble
Pour the chocolate topping over the caramel then chill to set.
Remove the whole caramel slice from the tray, then cut it into squares to serve.