Preheat the oven to 160°C / 325°F / Gas mark 3. Cut parchment paper into squares big enough to fit into your 12-holed muffin tin. You can use papercases if you don’t have any parchment paper.
In a small bowl, combine your butter and caster sugar together until smooth.
Sift in your flour and cocoa powder. Give the mixture a good mix and beat in your eggs. You can use a hand blender to make this bit a little quicker.
Keep mixing until it is a creamy consistency. Add the vanilla extract and mix again.
Spoon the batter into your parchment paper cases and place in the oven for 20 minutes. When done, a skewer inserted into them should come out clean.
When ready, leave to cool while you make the icing. Combine the water, icing sugar and vanilla extract together in a bowl mix until you get your required texture.
When the cakes are cool, drip the icing over them with a spoon .Allow to set before serving with the berries and mint leaves.
If you want, you can tie twine around the parchment cases to keep them in place and make it look a little prettier.