Place the chocolate hazelnut spread and milk in a bowl. Microwave in 10-second intervals until smooth and slightly runny. Do not overheat. Set aside to cool.

In a large bowl, add the double cream, cornflour, and icing sugar. Begin whisking until the mixture starts to thicken.

Slowly pour in the chocolate mixture while continuing to whisk.

Whip until stiff peaks form—this is key for a perfect Chocolate Hazelnut Mousse Recipe.

Gently fold in the chopped hazelnuts, reserving a small amount for garnish.

Spoon or pipe into serving glasses or ramekins.

Top with whipped cream, remaining hazelnuts, and a light dusting of cocoa powder if desired.