In a bowl, mix melted butter, sugar, and cocoa powder until well combined.
Add graham cracker crumbs and shredded coconut, stirring until fully mixed.
Press the mixture into the bottom of a greased 9x9 inch pan to form the base layer evenly.
In a separate bowl, beat together softened butter, powdered sugar, and custard powder until creamy.
Spread the custard mixture over the graham cracker base evenly.
Melt the chocolate chips with cocoa powder in a microwave or double boiler until smooth.
Pour the melted chocolate over the custard layer, spreading it evenly.
Refrigerate the pan for at least 2 hours to set the layers.
Cut into squares once set, and serve chilled.
Enjoy your delicious Nanaimo bars with coffee or tea!