Stir together the crushed cookies, melted butter, pecans and coconut in a bowl until the mixture is well combined. Press into the bottom of a 20x30cm baking dish, and refrigerate while making filling.
Beat cream cheese, sugar and custard powder in a large bowl with an electric mixer until light and fluffy, and beat in eggs, 1 at a time, beating each until fully incorporated before adding the next. Layer the filling over the base.
Bake in the preheated oven until the centre is almost set, about 40 minutes. Refrigerate the cheesecake until fully cold, at least 3 hours.
Melt the plain chocolate in a saucepan over very low heat with the cream, and stir until the mixture is smooth. Pour the chocolate mixture over the cheesecake, spread with a spatula to cover the middle layer, and chill until the topping is firm, 15 to 20 minutes. Serve cold. Store leftovers in fridge.