Pre-heat oven to 160 degrees Celsius and grease and line a 20cm round springform cake tin.
In the bowl of a stand mixer beat the butter, sugars and vanilla using the paddle attachment. Beat until light and fluffy.
Then add the eggs one at a time, beating well after each. Gently mix in the hazelnut meal until combined.
Add the self raising flour and gently fold in until combined.
Transfer the cake batter into the tin and smooth the top.
Bake for about 50 minutes or until the cake is springy to the touch and a skewer comes out clean when inserted into the cake.
Leave the cake to cool before removing from the tin.
To make the caramel, place the sugar into a small saucepan, and stir in the water. Place the pan over high heat, and stir to dissolve the sugar until it starts to bubble.
Then stop stirring (and don’t stir again or the caramel will crystallise), and leave to cook for a further couple of minutes or until the caramel has turned amber in colour. If the caramel isn’t cooking evenly, swirl the pan to encourage the caramel to colour evenly.
Reduce the heat to low, and add the cream. Carefully stir until the cream until it has combined with the caramel. Continue to stir and add the butter little by little so each piece has time to melt before the next is added.
Once all the butter has been added and is well combined, take the caramel off the heat. Remove 70g of the caramel into a separate bowl (to be used for the buttercream) and add 1 tsp espresso/coffee flavouring to the caramel remaining in the pan. Leave both to cool before using.
To make the icing, beat the butter using a stand mixer and the paddle attachment for 1-2 minutes, or until it is pale and creamy.
Add in the icing sugar, and beat for another 1-2 minutes or until the icing is fluffy.
Add 70g of the homemade caramel and mix until combined.
Spread the buttercream over the top of the cake, then decorate with the remaining homemade coffee caramel and the hazelnuts.