Chocolate (what else?!) and Hazelnut Easter Cake

I'll create any excuse to make a cake really - but its nice to push the culinary boat out every once in a while. This is really delicious it also happens to be gluten free. Take care when folding in all of the 'air added' ingredients and you'll end up with a really light cake. Topping it with chocolate turns this cake into a delicious giant gianduja experience.
I took this recipe from Bake by Rachel Allen, making a few tweaks of my own. I used a 7 1/2 inch loose bottom tin, greased and lined with parchment paper.

Ingredients:
200g (skin on) hazelnuts
1 tsp GF baking powder
100g softened butter
2 tbsp cocoa powder
5 eggs separated into two bowls
150g castor sugar
pinch of salt

1- Preheat fan oven to 160C.
2- Grind the hazelnuts in a food processor. I ground them as fine as my machine would allow me catching it just before it started to turn into hazelnut butter! Tip into a bowl and stir through the baking powder and cocoa powder before creaming in the butter.
3- With a hand held mixer whip the egg yolks and sugar until it becomes thick and mousse-y and the mixer leaves a trail. Carefully fold this into the hazelnut mixture.
4- Add the pinch of salt to the egg whites and whisk to stiff peak stage. Carefully fold this into the nut mixture in three stages.
5- Pour into the tin, giving it a few taps to even the surface. Bake for 40-45 minutes or until a skewer comes out clean.
6- Allow it to cool on cooling rack for about 20 minutes before removing from the tin. Then allow it to cool completely before adding the icing.

Ganache ingredients
100g 85% chocolate, broken into pieces
100ml cream
knob of butter
squeeze of honey (about 1/2 tbsp)

1- Heat the cream in a stainless steel pot over a gentle heat. Remove from heat just before it reaches boiling point.
2- Add the chocolate, butter and honey and allow to sit. The heat of the cream will melt the chocolate.
3- After 5-10 minutes stir everything together and allow to cool slightly before generously smearing the cake with the icing and licking the spoon clean.