• Preheat the oven to 350°F (180°C). Line a 20-cm x 20-cm (8-inch x 8-inch) square pan with parchment paper. You can also use a slice pan, but the slices are thinner and dryer after baking. Slightly oil paper with oil spray. Set aside.
• In a large mixing bowl, stir flour, crushed Weetbix, unsweetened cocoa powder, sugar, coconut, and baking powder. Set aside.
• In a non-stick saucepan, melt the margarine and dark chocolate under medium heat.
• Pour melted chocolate mixture, vanilla extract, and 3 teaspoons of boiling water onto the dry ingredients.
• Stir with a silicone spatula until consistent and easy to squeeze by hand. If it's too dry - doesn't stick together when squeezed stir in more boiling water one tablespoon at a time.
• Pour the batter onto the prepared pan and press firmly, evenly.
• Bake in the center rack of the oven for 10-15 minutes, until set on top but still soft. Don't overbake are the slice gets dry.
• Cool down in the pan then spread the ganache.

Ganache

• In a small bowl, stir icing sugar, cocoa powder, vanilla, and melted margarine. If too thin add more icing sugar, if too thick you can add more melted butter to thin it out. Spread on top of the bar and sprinkle coconut all over.
• Cool down 3 hours at room temperature on a wire rack before cutting into 16 Weetbix slices.

Storage

• Store in the fridge in a sealed box for up to 4 days or freeze for later.