Preheat the oven to 180°C (Gas mark 4/350°F). Line a 12 hole muffin tin with muffin cases.

Pop the butter into a mixing bowl then add the sugar and eggs.  Sift the flour, cocoa powder and baking powder on top and using an electric whisk on a low speed, gently blend the ingredients together. Add the black food colouring if using, then increase the mixer speed and whisk for a few more seconds until completely combined.

Divide the cake mixture equally between the muffin cases and smooth over the tops with the back of a spoon. Bake for 20-25 minutes until risen and springy to the touch. Transfer to a wire rack to cool.

Meanwhile, make the buttercream icing. Whisk the butter with an electric whisk until light and fluffy. Sift in the icing sugar, a little at a time, until completely combined. Add the vanilla extract and whisk again. Add the yellow food colouring, then add the milk in small splashes, whisking in between, until the icing is at the correct consistency for spreading.

Once the cakes are cooked, transfer to a wire rack to cool. Whilst the cakes are cooling, create the Batman themed toppers from the fondant icing ready to decorate the cakes.

To make the toppers, you will need a small bat shaped cutter and two circle cutters - one the same size as the top of your cupcakes, and one slightly smaller.

Using the cutters cut 6 large circles, 6 smaller circles and 6 bat shapes from the fondant. Repeat with the yellow fondant. You should end up with 12 of each shape - 6 of each colour.

Layer up the shapes in alternate colours, e.g. 1 large black circle, 1 smaller yellow circle and 1 black bat, or vice versa. Press gently together, or use a little water to stick the layers to each other if needed.