Preheat the oven on 170 degrees celcius (only the bottom part) and line a 9 inch rectangular baking dish with parchment, grease with tahini and sprinkle with sesame seeds, then leave it aside.
In a stand mixer, beat the eggs and the sugar on medium speed until creamy and light in color (around 6 minutes), then add the oil, milk, cardamom, water and saffron. Gradually add the Betty Crocker mix and beat all of the ingredients together for 2 – 3 minutes.
Pour the batter in the baking dish and bake for 25-35 minutes. When a wooden squewer comes out clean, remove the cake from the oven and turn it ouver a cooling rack, then leave to cool completely.
To make the Quors Akilil Trifle: In a pot, heat up 2 cups of milk, 3 tbsp. custard powder, 1 tbsp rosewater and 2 tbsp. sugar. Stir until thick, then keep aside.
Cut the cake into small slices. In a deep serving dish layer first the cake, followed by the custard and pistachio (optional). Add as many layer as you want, then decorate with pieces of cake or some berries and refrigerate for at least an hour before serving.