Preheat the oven to 350° Fahrenheit. Lightly grease a 9- by 9-inch glass baking dish with coconut oil cooking spray and line the bottom and sides with a big piece of parchment paper then lightly grease the parchment paper; set aside.
Mix together all of the shortbread ingredients, squashing most clumps with a fork. Press into the bottom of the prepared baking dish (if you have a second 9- by 9-inch baking dish that nests inside the first, use it to press down the shortbread layer).
Bake shortbread for 20 minutes or until the edges are light golden brown. Remove from the oven and set aside to cool.
Meanwhile, spread the shredded coconut over a baking sheet. Pop into the oven (still at 350°) for about 9 minutes, stirring every 3 minutes. Remove from oven and set aside.
Melt the butter then stir in the remaining ingredients. Measure ¼ cup of the liquid chocolate layer and set that bit aside.
Once remaining chocolate has cooled down a bit, pour or spread it over the surface of the shortbread in the baking dish. Pop in the freezer for about 10 minutes or until the chocolate is firm.
Spread the coconut-caramel mixture over the chocolate layer. Cover the dish and refrigerate for 45 minutes to an hour.
Once the bars are firm, pull them out of the dish carefully by lifting up the parchment paper. Cut into 16 squares.
Drizzle the reserved chocolate over the tops of the bars, melting down again if necessary. Alternatively, you could wait until the chocolate is a frosting-like consistency then put it into a pastry bag or plastic zip bag with the tip/corner snipped off and pipe ribbons of chocolate over each bar (this is what I did for the picture).