Chocolate and Hazelnut Cake

For the cake
400g shelled dried hazelnuts
1 tsp cocoa powder 
250g dark chocolate, about 70%, broken into pieces
200g butter, plus a little more for greasing the tin, softened
200g caster sugar 
5 egg yolks 
Pinch of salt
1 tbsp brandy (optional)

For the chocolate glaze
100g caster sugar
50g dark chocolate (about 70%) 
20g butter

Heat the oven to 200C/400F/gas mark 6. Put the hazelnuts on a baking tray and roast until browned, checking regularly they aren't burning – about five minutes.

Turn down the heat to 150C/300F/gas mark 2. Tip the hazelnuts into a clean tea towel, wrap them up and leave for a minute, then rub vigorously with the tea towel to loosen and remove their papery skins. When cool, reserve about 30g of the nuts to garnish the cake at the end and pulse the rest in a food processor until fine.

Grease the bottom and sides of a 23cm springform tin, then dust the insides with cocoa powder. Line the base with baking parchment and butter the parchment.

Put the chocolate in a heatproof bowl and place over a pan of barely simmering water – the water should not touch the bottom of the bowl. Melt the chocolate, remove the bowl from the pan and leave to cool.

With a stand mixer or hand mixer, beat together the butter and sugar until light and fluffy. Add the egg yolks one at a time, beating well after each addition and adding a pinch of salt with the last yolk. With a rubber spatula, fold in first the hazelnuts and then the chocolate and alcohol, if using. Spoon into the tin, smooth over the top and bake for about 45 minutes, until a toothpick inserted into the middle comes out with just a few moist crumbs clinging to it. Place the tin on a wire rack and leave for 20 minutes before releasing the sides of the cake tin and leaving to cool completely. Invert the cake on to a plate, and remove the base and the paper.

To make the glaze, tip the sugar into a small pan with 100ml water and warm over a low heat, stirring to dissolve the sugar. Bring to a boil and boil hard for three minutes. Remove from the heat and cool until it's very warm, rather than volcanically hot (you can put the base of the pan into the sink filled with a couple of centimetres of cold water to speed this up). Stir in the chocolate and butter until it's melted, blended and glossy. Pour over the cake and finish with the remaining nuts.