Ingredients         115g/4oz unsalted butter, softened, plus extra for greasing         170g/6oz caster sugar         2 free-range eggs         40g/1½ oz plain chocolate (minimum 65% cocoa solids)         55g/2oz pecans (optional)         1 tsp vanilla extract         2 tsp instant coffee granules         2 tbsp warm water         1 tsp baking powder         55g/2oz plain flour         55g/2oz cocoa powder To serve         icing sugar, for dusting Preparation method     1-Preheat the oven to 180C/350F/Gas 4.     2-Prepare the cake tin. Grease an 18cm/7in square cake tin and line with non-stick baking parchment.     3-In a clean bowl, cream together the butter and sugar until pale and fluffy. Beat in the eggs, one at a time.     4-Chop the chocolate and put to one side.     5-Chop the pecans, if using. Gently fold the nuts and chocolate into the butter and egg mixture. Add the vanilla extract.     6-Dissolve the coffee granules in two tablespoons of warm water and add to the mixture. Mix together well.     7-Add the baking powder, then sift in the flour and cocoa powder. Mix well; the mixture will be quite wet.     8-Spoon the brownie batter into the prepared tin and level out the top with a spatula.     9-Bake in the oven for 35-40 minutes. Allow to cool in the tin for ten minutes, then place on a wire rack to cool.     10-To serve, cut into rectangles and dust with icing sugar. From BBC food