1.Sift flour and cocoa together into a large bowl. Stir in sugar. Whisk in combined milk, eggs and butter. Stand for 30 minutes.
2.To make chocolate custard, whisk yolks, sugar and cornflour together in a medium bowl. Bring combined milk and cream to the boil in a saucepan on medium heat. Remove from heat. Gradually whisk into yolk mixture. Return custard mixture to saucepan. Stir in chocolate. Heat, stirring constantly, on low heat until mixture thickens and coats the back of a spoon. Do not boil. Remove custard from heat.
3.Spray a large frying pan with oil and heat on medium. Cook ¼-cup measures of pancake mixture for 2-3 minutes, until bubbles form on surface. Turn and cook for a further 2 minutes. Repeat with remaining batter, spraying pan with oil as required. Serve warm pancakes drizzled with chocolate custard. Sprinkle with berries and grated chocolate.