Melt dark chocolate over double boiler, pour into skull molds, and chill until set.
Preheat to 180°C (356°F). Line 12-hole cupcake tin with liners.
Stir soy milk and vinegar, rest 10 minutes.
Add coffee, apple puree, oil, and vanilla. Mix.
Whisk flour, cocoa, baking soda, salt, caster sugar, and muscovado.
Pour wet into dry, whisk gently.
Divide batter, bake 22–25 minutes. Cool on rack.
Simmer blackberries, sugar, water for 12 minutes. Cool. Reserve 2 tbsp.
Core cupcakes, fill with coulis, replace tops.
Split buttercream, add coulis to one, cocoa to other.
Alternate frostings in bag, pipe swirls.
Top with skulls and fresh blackberries.
