Nanaimo Bars (Canadian Dessert)

We start by making the cookie base. In a bowl over a saucepan of boiling water, melt the butter with the sugar and cocoa powder, stirring occasionally until smooth. Beat the egg for 2 to 3 minutes until the mixture thickens. Remove from the heat and mix in the biscuit crumbs, coconut and almonds, if using, then press into the base of a lined 20cm square tin. Cool for 10 minutes.
For the middle layer, make the custard glaze; Mix the butter, cream and custard powder until light and fluffy, then gradually add the icing sugar until fully incorporated. Spread on the bottom layer and chill in the refrigerator for at least 10 minutes until the cream is no longer soft.
Melt the chocolate and butter in the microwave, then spread over the cold bars and return to the refrigerator. Leave until the chocolate has completely set (about 2 hours). Take the mixture out of the mold and cut it into squares to serve.

foods：
125 g custard
50 g powdered sugar
5 tablespoons of cocoa
1 beaten egg
200 g grated digestive biscuits
100 g desiccated coconut
50g almonds
100g butter
4 tablespoons double cream
3 tablespoons custard powder
250 g icing sugar
150 g dark chocolate
50g butter