Chocolate and Hazelnut Bûche de Noel

Here is another Bûche de Noel recipe! Of course the method is the same, however, the components are different.  That is the great thing about Bûche de Noel; you can fill it with whatever ingredients or creams you desire.  For this, I thought that Hazelnut Buttercream Filling with Chocolate Buttercream on the outside would be divine.  Let me tell you, I was spot on!

Ingredients for Sponge Sheet
4 eggs
100g caster sugar
100g plain flour

Method
In a bowl, beat the eggs lightly to disperse the yolk (by hand or with mixer if needed).  Add the sugar and continue to whisk/electric mix the egg and sugar until the sugar dissolves and pale ribbons form.  At this stage, fold in 1/3 of flour; continue to fold until no flour remains.  Spread the sponge mixture on a tray lined with baking paper.  Bake at 180 degrees (fan-forced) until golden and just firm; perhaps 15 minutes.  The sponge should spring back when cooked properly.  Remove sponge from oven and immediately begin to roll it by rolling it from the shortest edge.  Allow to cool.

Ingredients for Hazelnut Buttercream Filling
125g butter, cubed, at room temperature
1 1/2 cup icing sugar, sifted
2 tbsp milk, at room temperature
1/2 cup hazelnuts 

Method
Process the [unshelled] hazelnuts in a food processor.  You don't want them as fine as almond meal/powdered almond but you don't want them chunky.  Set aside hazelnuts.  Now make the buttercream.  It is important to have the butter and milk at room temperature.  Place cubes of butter in a large mixing bowl.  Cream until the butter is as white as possible, say 2 minutes.  Very gradually add half of the sifted icing sugar; beating continuously.  Gradually add the milk; beating continuously.  Very gradually add the rest of the icing sugar; beating continuously.  Icing should be a smooth and spreadable consistency.  Stir through the chopped hazelnuts. 

Ingredients for Chocolate Buttercream
125g butter, cubed, at room temperature
1 1/2 cup icing sugar, sifted
2 tbsp milk, at room temperature
1/2 cup cocoa powder

Method
It is important to have the butter and milk at room temperature.  Place cubes of butter in a large mixing bowl.  Cream until the butter is as white as possible, say 2 minutes.  Very gradually add half of the sifted icing sugar; beating continuously.  Gradually add the milk; beating continuously.  Very gradually add the rest of the icing sugar; beating continuously.  Add cocoa powder; beat in.  Icing should be a smooth and spreadable consistency.  

Method for Assembly
Unroll sponge cake.  Chop off any crusty edges. Ensure the side you frost is the bumpy side (as it was exposed to oven).  Spread all of hazelnut buttercream on this side.  Roll up by taking the short end of the sponge and rolling it to meet the other short end.  Place sponge on a plate.  Cover in chocolate buttercream. Cut diagonal slice of each end of the sponge so each end looks more like a log. You can place these bits of extra cake on top of the cake, or you can eat them, or discard them. Now, run a fork from one end of cake to other.  Place decorations on top.  Allow to chill in fridge for 1 hour before serving.