In a saucepan, whisk together the orange juice, egg yolks, vanilla sugar, sugar, and cornstarch until smooth.
Place the saucepan over medium heat and stir continuously until the mixture thickens.
Reduce the heat and add the butter, powdered sugar, and 80 ml of room-temperature milk. Stir until well combined.
Gradually add 500 ml of milk while stirring, ensuring a smooth consistency.
Mix in the lemon zest, lemon juice, and condensed milk, stirring well to incorporate all the flavors.
Pour the mixture into serving glasses or a dish. Let it cool slightly before refrigerating for at least 2 hours.
Before serving, sprinkle with cocoa or cinnamon and garnish with chocolate shavings. Enjoy chilled!