To make the Praline: Line a baking sheet with baking or greaseproof paper. Place the hazelnuts on the baking sheet in a single layer.
In a heavy based pan mix together sugar and water. Once the sugar has melted increase the heat to medium-high , swirling the pan occasionally, until the sugar begins to caramelise(deep amber colour).
Immediately remove the saucepan from the heat and pour the caramel over the hazelnuts.
Leave the praline to cool for 20 minutes or until hardened, then break into pieces. Grind to a fine powder in a coffee grinder or food processor.
Place chocolate in a heatproof bowl and sit over a pan of barely simmering water and allow chocolate to melt , stirring occasionally. Set aside once melted.
Add milk, cream and praline powder to a saucepan and stir in melted chocolate. Bring to a low boil, stirring occasionally.
Divide hot chocolate between 2 mugs and top with whipped cream.