Ingredients
8 oz dark muscovado sugar6 oz unsalted butter, preferably European or Plugrá
350 g 70% best quality dark chocolate, chopped into pieces
3 medium eggs
2 oz all-purpose flour
1 tsp baking powder
Method
Preheat oven to gas 5. Line a 20cm square tin with baking parchment. My Williams-Sonoma square cake pan is perfect for the job.Melt the chocolate and butter in a heatproof bowl over a pan of simmering water. Whisk the eggs until pale and fluffy. Add the sugar and whisk until thick. Gently fold in the chocolate. Sift in the flour and fold in until the mixture is smooth.
Pour the mixture into the prepared tin and bake for 30-35 minutes, until a paper-like crust forms on top. There should still be some movement in the center of the tin. Remove from the oven, leave to cool, then cut into squares.