Preheat your oven to 180°C/350°F/gas 4. Line a 25cm square baking tin with greaseproof paper. In a large bowl over some simmering water, melt the butter and the chocolate and mix until smooth. Add the cherries and nuts, if you?re using them, and stir together. In a separate bowl, mix together the cocoa powder, flour, baking powder and sugar, then add this to the chocolate, cherry and nut mixture. Stir together well. Beat the eggs and mix in until you have a silky consistency.
Pour your brownie mix into the baking tray, and place in the oven for around 25 minutes. You don?t want to overcook them so, unlike cakes, you don?t want a skewer to come out all clean. The brownies should be slightly springy on the outside but still gooey in the middle. Allow to cool in the tray, then carefully transfer to a large chopping board and cut into chunky squares. These make a fantastic dessert served with a dollop of cr?me fraîche mixed with some orange zest.