Preheat your oven to 180°C and line a two cupcake pans with cupcake paper cases.
Place the butter into a bowl of an electric mixer fitted with a whisk attachment. Beat the butter on high speed until it is white and fluffy this should take about 5 minutes.
Add the sugar and beat for another minute.
Add your eggs, one at a time and waiting at least one minute between each addition. Scrape the side of the bowl with a spatula to ensure the mixture is beating evenly.
Sift the flour, salt, cocoa power and baking powder into a separate bowl and set aside.
Combine the milk, vanilla and coffee into a jug.
Alternate by adding the dry and wet ingredients to the egg mixture on medium to low speed. Scraping down the sides of the bowl to ensure that the mixture is lump free and mixing evenly.
Fill the cupcakes cakes ¾ of the way full and bake in a preheated oven for 15 minutes.
Allow to cool before icing.
Mulberry Icing
Wash the mulberries and ensure that you have removed the green stalks from each one.
Place the mulberries and the sugar in a small pan over medium heat. Allow the sugar to melt and for the mulberries to release their juices.
Remove from the heat and blend until smooth in a food processor. Pass the mixture through a sieve to remove the seeds or leave the seeds for extra colour. Allow the mixture to cool completely before using it in the icing.
Place the butter into a bowl of an electric mixer fitted with a whisk attachment, beat the butter on high speed until it is white and fluffy. Ensure that you have scraped down the sides of the bowl so that there is no yellow butter on the sides.
Change the whisk attachment to the paddle attachment and add the icing sugar. Beat the butter and icing sugar until fluffy.
Add the cream and two tablespoons of the cooled mulberry mixture and continue to beat until the mixture if fluffy and suitable for piping.
Add the mixture to a pipping bag fitted with your chosen nozzle and pipe each cupcake with a swirl icing. Enjoy!