Heat oven to 180°C for 15 minutes.
Place a Chefs Toolbox Baking Sheet on a baking tray, place coconut on the sheet, and toast in the oven until coconut is golden brown for approximately 7 minutes. Place Mars Bars and butter in an advanced 2L Saucepan over medium heat.
Whisk to combine as the chocolate and butter melts.
Place coconut and Rice Bubbles in a large bowl. Pour over the chocolate mixture and mix well to combine.
Press mixture into Chefs Toolbox Baking Tray, then place in refrigerator until set, at least 30 minutes.
Melt the remaining chocolate and spread it over the slice. Return to the refrigerator for 10 minutes to set.
Cut into small portions and serve