Double chocolate and mascarpone traybake

Ingredients

• 100g unsalted butter, plus extra for greasing
• 75g dark chocolate
• 220g plain flour
• 45g cocoa powder
• 280g light brown sugar
• 2 tsp baking powder
• ½ tsp bicarbonate of soda
• ½ tsp flaky salt
• 3 large eggs
• 2 tbsp vegetable oil
• 100ml whole milk

Frosting

• 170g milk chocolate, plus extra shaved chocolate to finish
• 60g unsalted butter
• 25g cocoa powder
• 200ml double cream
• A pinch of flaky salt
• 125g mascarpone, at room temperature

Directions

1. Preheat oven to 180°C (160 fan). Grease a 23cm x 33cm baking tin, then line it with greaseproof paper, leaving enough overhang to help you lift out the cake once baked.
2. For the cake, put the chocolate and butter in a heatproof bowl and melt in short bursts in a microwave or over a pan of simmering water. Set aside to cool.
3. In a large bowl, mix the flour, cocoa powder, sugar, baking powder, bicarb and salt. Make a well in the centre, pour in the eggs, oil, milk and cooled chocolate/butter mix, and whisk to a thick, smooth batter. Pour in 150ml hot water and mix again until well combined.
4. Pour the batter into the prepared tin, then bake for 35-40 minutes, or until a skewer inserted into the middle comes out clean. Take out of the oven and leave to cool.
5. Meanwhile, make the frosting. Put the chocolate, butter, cocoa powder, half the cream and the salt in a small saucepan and heat very gently until just melted.
6. Put the mascarpone in a bowl, pour the chocolate mixture over it, then whisk well to combine. Add the rest of the cream, mix until smooth, then leave to cool and thicken to to a spreadable consistency.
7. Spread the frosting all over the top and sides of the cake, top with shaved chocolate, then slice and serve.