Melt the 70% Dark Chocolate (160 gram) and Unsalted Butter (2 tablespoon) in a bowl over boiling water. When melted set aside to cool down.
In a pot, add the Milk (1 liter), Granulated Sugar (135 gram), and Vanilla Extract (1/2 teaspoon) and leave to warm up in medium heat until the milk starts to froth.
Add the chocolate, Egg (4) and Corn Starch (3 tablespoon) mix constantly for approximately 8 minutes until the chocolate has thickened. Set aside to cool down.
In a tray, start to build the layers of Digestive Biscuit (300 gram) and chocolate by dunking the biscuits in milk and placing them on the tray. Build the layers until finishing all the ingredients leaving some chocolate for the top.
Finish the cake with a layer of chocolate and sprinkle some roasted almond flakes, or crunched pistachios or even grated chocolate. Cover the tray with cling film and place in the fridge over night. Serve and enjoy!