Preheat the oven to 325° F / 160° C / 140° Fan / Gas 3.

Line a muffin tin with 12 large muffin sized cupcake cases.

Cream together the butter and sugar until pale and creamy.

Slowly add the beaten eggs.

Add the flour and mix thoroughly until smooth.

In a small bowl or cup mix together 2 heaped tsps of the milkshake powder with 15ml of the milk until it forms a smooth paste.

Add the paste and a few drops of yellow colouring to the batter and mix thoroughly.

Carefully spoon the batter into the cases.

Bake for around 25 minutes or until the sponge springs back when pressed lightly.

Remove from the tin and leave to cool on a wire rack.

Add the softened butter to the icing sugar and mix together until creamy and lump free.

In a small bowl or cup mix together the remaining milkshake powder and milk until it forms a smooth paste.

Add the paste and a few drops of yellow colouring to the buttercream and mix in until completely blended.

Once the cakes are cool pipe a swirl of frosting onto each cake and top with banana milkshake sweets.