1. Preheat the oven to 160°C/325°F/Gas Mark 3.
2. Put the Stork and the chocolate into a heat proof bowl over a saucepan with hot water and leave until melted (alternatively, microwave on medium power, stirring occasionally, until just melted). Stir until smooth.
3. In a separate bowl, whisk the eggs with the sugar and vanilla until slightly thickened. Whisk in the chocolate mixture.
4. Sieve the flour, baking powder, cocoa and a pinch of salt over the bowl and fold into the batter. Finally fold in the chopped walnuts.
5. Spoon the batter into the prepared cake tin. Bake in the preheated oven for 40-50 minutes until cooked. Cool in the tin before cutting into squares.
Don’t like nuts? You can swap the nuts for 55g chocolate chunks or your favourite candies.
Recipe courtesy of Stork