1.Preheat oven to 180°C. Line four 12-hole (1-tablespoon/20ml) mini muffin pans with paper cases.
2.Beat butter, extract, sugar, eggs, sifted flour and wine in a small bowl with an electric mixer on low speed until ingredients are combined. Increase speed to medium; beat until mixture has changed to a paler colour. Drop 2 level teaspoons of mixture into each paper case.
3.Bake cupcakes about 12 minutes. Leave cakes in pan for 5 minutes before turning, top-side up, onto a wire rack to cool.
4.Make champagne butter cream: beat butter in a small bowl with an electric mixer until as white as possible. Beat in sifted icing sugar and wine, in two batches.
5.Spoon butter cream into a large piping bag fitted with a large fluted tube. Pipe swirls of butter cream on top of each cake. Sprinkle with sanding sugar and sugar pearls.
Sanding sugar is a decorating sugar that adds colour and sparkle; it also holds its shape and colour after baking. It is available in a range of colours from specialist food and cake decorating stores. Uniced cakes can be made a day ahead or frozen for up to 3 months.