Preheat your oven to 180°C (160°C fan) and line a cupcake pan with cupcake liners.

In a medium bowl, sift together the plain flour, bicarbonate of soda, and salt.

In another bowl, whisk together cocoa powder and coffee granules, then pour in the boiling water. Stir until the mixture is smooth.

In a large mixing bowl, cream the softened butter and soft light brown sugar using an electric mixer until fluffy.

Add the eggs one at a time, followed by the vanilla extract, mixing well after each addition.

Pour the cooled cocoa mixture into the creamed butter and sugar, gently mixing until combined.

Carefully fold the dry ingredient mixture into the wet ingredients using a spatula.

Spoon the chocolate batter into the lined cupcake pan, filling each liner about two-thirds full.

Place the cupcake pan in the preheated oven and bake for 18–22 minutes.

In a clean mixing bowl, beat the softened butter and icing sugar together until light and fluffy.

Gradually add the milk and mix until the buttercream is smooth and spreadable.

Once the cupcakes are completely cool, pipe the buttercream onto each one.

Using a small knife, carefully core the center of each cupcake to create room for the Cadbury mini creme eggs.

Top off each cupcake with a swirl of the remaining buttercream and place half a mini creme egg on top.