1. Preheat and Prepare:
- Preheat the oven to 160°C Fan/180°C/350°F/Gas Mark 4.
- Grease and line a 2lb loaf tin with baking paper or use a loaf tin liner.
2. Make the Sponge:
- Dissolve the coffee granules in the boiling water and set aside.
- In a large bowl, beat the butter and sugar together until light and fluffy.
- Add the eggs and coffee mixture, whisking until smooth.
- Sift in the flour, cocoa powder, and baking powder, then mix until fully combined.
- Pour the batter into the prepared loaf tin and bake for 1 hour 10 minutes, or until a skewer inserted into the center comes out clean.
- Let the cake cool completely in the tin before removing.
3. Prepare the Buttercream:
- Beat the butter and icing sugar together until combined.
- Add the vanilla extract and milk, mixing until smooth. Adjust the milk as needed for a spreadable consistency.
- Divide the buttercream into three bowls. Color one pink, one purple, and one yellow using food coloring.
4. Decorate the Cake:
- Spread each colored buttercream in a line on a sheet of cling film, placing them side by side.
- Roll the cling film into a sausage shape, then snip one end and pipe the buttercream onto the cake using a piping bag. Alternatively, spread the buttercream in blobs of each color.
- Decorate with Mini Eggs on top.