225g dark chocolate (70% cocoa solids), finely chopped
125g butter, diced
175g caster sugar
1 tsp vanilla extract
100g ground almonds
6 large eggs, separated
To make the peanut brittle, grease a large baking sheet with a little oil. Combine the sugar with 120ml of water in a heavy-based saucepan over a medium-high heat and bring to the boil. Then reduce the heat slightly and allow the mixture to simmer steadily for about 15 minutes, without stirring, until a golden caramel forms. Swirl the pan to encourage the sugar to caramelise.
Remove the pan from the heat and stir through the peanuts. Spread the mixture on the prepared baking sheet and allow to set for 30 minutes. Break up the brittle and bash in a pestle and mortar to a rough crumb.
Wash and dry the saucepan ready for the salted caramel.
To make the salted caramel, this time combine the sugar with 50ml of water in a heavy-based saucepan over a medium-high heat and bring to the boil. Then reduce the heat slightly and cook the caramel as for the peanut brittle, making sure not to disturb it until the caramel has formed.
Remove the pan from the heat and pour in the cream and salt and mix through. Don't panic when it bubbles and spits: return the pan to a low heat and the sugar crystals will re-melt. Add the butter and mix through to form a smooth caramel.
Preheat the oven to 180°C (350°F), Gas Mark 4 and line a 20cm diameter springform tin with baking parchment.
For the mud pie, melt the chocolate and butter in a large heatproof bowl sitting over a saucepan of barely simmering water.
Remove the bowl from the heat and mix in the sugar, vanilla extract and ground almonds with a spatula. Stir through the egg yolks, one at a time, mixing after each addition, until you have a thick batter.
Put the egg whites in a standing food mixer (or use an electric hand-held mixer in a bowl) and whisk the egg whites until stiff peaks form. Add the egg whites to the chocolate batter and fold through gently until just combined.
Pour two-thirds of the chocolate batter into the prepared cake tin. Using a spoon, pour over the caramel in an even layer, then cover with the remaining batter and place the tin in the oven to bake for about 35 minutes until it is firm but with a slight wobble.
Remove the cake from the oven and allow it to sit on a wire rack to cool in its tin.
Carefully remove the mud pie from the tin and transfer it to a cake stand with a lip to catch the caramel as it oozes out while still a little warm. Sprinkle with the peanut brittle and serve in generous slices.