Creamy Vanilla Pudding with Milk Chocolate and Hazelnut Topping

Steps on How to Do It:
Prepare the Pudding Base:
In a medium saucepan, combine the milk, sugar, and vanilla sugar. Whisk everything together over medium heat until the sugar dissolves, but do not let it boil yet.
Thicken the Pudding:
In a small bowl, mix the flour and corn starch with a few tablespoons of cold milk (from the 500 ml) until smooth. This slurry will prevent lumps from forming when added to the hot milk.
Slowly pour the flour-corn starch mixture into the saucepan with the heated milk, whisking constantly to prevent clumping.

Continue cooking the mixture over medium heat, stirring constantly, until the pudding thickens. This will take about 5-7 minutes. Once the mixture starts to bubble and thickens to a creamy consistency, remove it from heat.
Add Butter for Extra Creaminess:
Stir in the 20 g of butter while the pudding is still hot, whisking until the butter is fully melted and incorporated. This adds richness and a silky texture to the pudding.
Cool the Pudding:
Pour the hot pudding into individual serving bowls or molds (each about 8 cm in diameter for three servings). Let the pudding cool at room temperature for 10 minutes, then cover the tops with plastic wrap to prevent a skin from forming. Place the pudding in the refrigerator to chill for at least 1 hour, or until fully set.
Prepare the Toppings:
While the pudding is chilling, prepare the toppings. Melt the 20 g of milk chocolate in the microwave in short 20-second intervals, stirring between each interval until smooth and fully melted.