Preheat your oven to 160C Fan/180C/350F/Gas Mark 4 and line a cupcake tin with black cupcake cases.
Whisk together 150g of softened butter and 150g of caster sugar until fluffy and light.
Add in two large eggs and one teaspoon of vanilla extract, mixing until well combined.
Combine 85ml of buttermilk, 165g of self-raising flour, 1½ tablespoons of cocoa powder, ½ teaspoon of bicarbonate of soda, and one teaspoon of red food coloring into the bowl and mix until just combined.
Divide the batter evenly among the lined cupcake cases, filling them about two-thirds full, and bake for 20-25 minutes.
Transfer the cupcakes to a cooling rack and let them cool completely.
Use a cupcake corer or a small knife to create a hole in the center of each cupcake and fill with strawberry or raspberry jam.