Ingredients
Equipment
Method
Make the Base:
- Line an 8-inch square pan with parchment, leaving an overhang.
- Melt the butter, sugar, and cocoa in a heatproof bowl set over barely simmering water. Whisk in the egg and cook for 2 to 3 minutes, until slightly thickened.
- Remove from the heat and stir in the graham crumbs, coconut, and walnuts. Press firmly and evenly into the pan, then chill for 20 minutes.
Add the Custard Layer:
- Beat the softened butter and custard powder until smooth. Beat in the milk, then add the icing sugar gradually until the filling is light and cohesive.
- Spread over the chilled base with broad strokes. Chill for 45 minutes, until firm.
Top and Cut:
- Melt the chocolate and butter together gently. Cool for 5 minutes, then spread a thin layer over the custard filling.
- Chill for 20 minutes, score the chocolate into 16 pieces, then chill for at least 1 hour more.
- Lift from the pan and cut along the score lines with a warm dry knife.
Nutrition
Notes
- Score the chocolate before it becomes fully hard to reduce cracking when the bars are cut.
- Store covered in the refrigerator for up to five days, or freeze with parchment between layers.