Preheat oven and line pan:

Heat the oven to 350°F (175°C). Place 12 paper liners in a 12-cup muffin pan.

Cream butter and sugar:

In a bowl, cream the softened butter or dairy-free spread with the golden caster sugar using an electric mixer until pale and fluffy. In another bowl, lightly beat the eggs, then gradually add them to the butter mixture, beating well after each addition.

Sift flour and mix batter:

Sift the self-rising flour over the batter and fold in on low speed with an electric whisk. Add the milk and vanilla extract, mix again, then increase speed and beat briefly until smooth.

Fill liners and bake:

Evenly distribute the batter among the 12 liners and level the tops with a spoon. Bake for 20–25 minutes until the cupcakes are risen, golden, and bounce back when touched. Move to a wire rack and let cool entirely.

Make vanilla buttercream:

To make the buttercream: Beat the softened butter with an electric mixer until light and creamy. Gradually sift in the powdered sugar and beat until well incorporated. Add the vanilla extract and mix again.

Tint buttercream green:

Add the green gel food coloring and beat until the color is uniform. Add the milk a little at a time until the buttercream reaches a consistency suitable for piping.

Pipe grass tufts:

Transfer the buttercream to a piping bag fitted with a grass tip. Pipe grass-like tufts onto each fully cooled cupcake.

Place bunny and secure:

Set one Maltesers Mini Bunny in the middle of each cupcake, pressing slightly into the buttercream. Pipe a few extra grass tufts behind each bunny to keep it upright.

Arrange mini eggs:

Arrange a few mini eggs around each bunny on top of the buttercream.