Roast the hazelnuts - Pre-heat the oven to 150 degree C. Place the hazelnuts in a baking pan and roast them for 15-20 minutes. Let them cool and grind them to a fine powder.
Pre-heat the oven to 180 degree C. Line a 7 or 8 inch pan with parchment or grease it well.
In a large bowl, melt the butter and chocolate together.
Add to it, the caster sugar, all-purpose flour and the ground hazelnuts.
Finally add the milk and mix to make a smooth batter. Don’t overmix.
Transfer to the prepared pan.
Bake in the pre-heated oven for 25-30 minutes or until the cake slightly leaves the sides of the pan.
Let cool slightly, then serve warm.