Ingredients

Step by step

1. Preheat the oven to 190°C, fan 170°C, gas 5. Line a 12-hole muffin tray with deep cupcake cases (black or dark brown look dramatic).
2. Beat the butter and sugars together in a mixing bowl – either with a wooden spoon, a handheld electric whisk or freestanding mixer and paddle attachment. This won't go fluffy, as there is much more sugar than butter, but try to get it as smooth as possible. Beat in the eggs. Sift the flour, cocoa powder and bicarbonate of soda together into a bowl and fold this in, alternating with the buttermilk, until well combined. Pour over the Guinness and fold in until you have a smooth batter.
3. Divide the batter between the muffin cases. Bake for 20-25 minutes, until a skewer inserted into the centre comes out clean. Cool on a wire rack, in the muffin tray. Don't turn off the oven.
   Tip

   Weigh the Guinness rather than measuring it out in a jug, as the froth can often impede an accurate reading, and weight is far more accurate than volume. Any leftover Guinness can be drunk or saved for use in a beef casserole or stew.
4. For the 'glass' shards, unwrap the mints and grind them to a fine powder – I do this in my NutriBullet, but you can do it in an ordinary food processor. Line a baking sheet with a piece of baking paper and sprinkle the powdered sweets onto the baking paper as evenly as possible. Heat in the oven until it forms a molten pool of 'glass' – about 10 minutes. Remove from the oven and allow to cool and harden completely.
5. For the filling, put the jam into a sieve over a bowl and press the jam though to remove the seeds and skins. Set aside 3 tablespoons of the sieved jam for the icing. Mix the remaining sieved jam with 3 tablespoons cassis. Remove and reserve 3 tablespoons of this mixture to use later as a 'blood dribble'.
6. Use a small sharp knife (or an apple corer) to remove a small round of cake (about 2cm) from the middle of each cupcake, to create a cavity – be careful not to press right through to the base of the cupcake – and set aside these pieces of cake, don't discard. Using a small teaspoon, divide the cassis jam filling between the cavities of the cupcakes (see recipe introduction) and plug the tops with the reserved little pieces of cake, to enclose the filling.
7. For the purple cassis icing, whisk the butter in a bowl until pale and light. Sift over the icing sugar in 2 or 3 batches, whisking with each addition until light and creamy. Add the reserved 3 tablespoons sieved jam and 1 tablespoon cassis, plus as much of the gel food colour as you want.
8. To assemble, cover the tops of each cupcake with the icing using either a piping bag fitted with a 15mm nozzle, or a small palette knife or spoon to spread the icing.
9. Break the 'glass' into sharp shards. Insert one big shard into each cupcake, with a drizzle of the reserved jam and cassis mixture as blood.