Prepare an 8-inch square baking dish with parchment paper on the bottom.
In a double boiler, melt the butter, sugar, and cocoa powder. Add the beaten egg and whisk for 2 minutes until thickened and the egg is cooked through.
Remove from the heat and stir in the graham cracker crumbs, shredded coconut, and roasted almonds. Press into an even layer in the baking dish.
In a stand mixer with the whisk attachment (or hand beater), beat the butter, cream, custard powder, and icing sugar until soft and fluffy, about 3 minutes.
Pour into the baking dish and use a rubber spatula to gently spread it into an even layer. Transfer to the fridge for 30 minutes to firm up.
Melt the butter and chocolate in the microwave or in the double boiler. Let it cool for about 5 minutes then spread it evenly as the final layer. Transfer to the fridge to chill and once the chocolate is set, it is ready to eat!
To remove it from the baking dish, use a knife to cut around the edges then invert it onto a cutting board.