Preheat oven to 190°C/375°F/Gas Mark 4 and place a baking tray in the upper part. Grease a 1.5 litre (2 ½ pints) ceramic dish with butter and scatter cherries in evenly. Sift flour and baking powder into a bowl and whisk in half the sugar. Make a well in the centre.
Beat eggs with remaining sugar, then whisk in half the milk. Pour this mixture into the well and beat until you have a lump-free batter. Beat in remaining milk, kirsch and chocolate.
Pour the batter over cherries and place in the oven. Bake until the batter is golden on top and cooked through, about 30 minutes. Test with a skewer – it should come out clean (although the chocolate will stick a little to the skewer). Take from the oven and dredge liberally with icing sugar.