Muffins can be made up to three days ahead. Store in an airtight container. If ganache becomes too thick, return bowl to simmering water and stir until desired consistency. Ganache is ready when it is a spreadable consistency.
Cooking oil spray
150g dark cooking chocolate, chopped
150g unsalted butter, chopped
1/3 cup brown sugar, firmly packed
3⁄4 cup buttermilk
2 eggs, lightly beaten
11/3 cups self-raising flour
2 tblsps cocoa powder
125g punnet fresh raspberries
Extra fresh raspberries and icing sugar mixture, to decorate
100g dark cooking chocolate, chopped
1⁄4 cup pure cream
Generously spray a non-stick 6-hole Texas muffin pan (3⁄4-cup capacity) with oil.
Place chocolate and butter in a large heatproof bowl. Sit bowl over a saucepan of simmering water. Stir until melted. Remove. Cool slightly.
Whisk sugar into cooled chocolate mixture until combined. Add buttermilk, eggs and combined sifted flour and cocoa. Stir until combined. Gently fold in raspberries. Divide evenly among prepared pan holes.
Cook in a moderate oven (180C) for about 25 minutes, or until a skewer inserted into the centre comes out clean. Stand in pan for 20 minutes. Transfer to a wire rack to cool.
To make ganache, combine chocolate and cream in a heatproof bowl. Sit bowl over a saucepan of simmering water. Stir until smooth. Refrigerate for about 30 to 40 minutes, stirring occasionally, until thickened.
Spoon ganache on top of each muffin. Decorate with extra raspberries. Dust with icing sugar.