Makes 12 mermaid tails which are best made in advance and allowed to set overnight.

Take the white fondant out of the foil and knead on a surface lightly dusted with icing sugar until it is soft and pliable. Divide fondant into 2 equal sized balls.

Take the 1st ball of fondant and add approx. ¼ tsp of Blue Colour Gel, kneading until the colour is evenly mixed. Repeat with the 2nd ball of fondant adding approx.. ¼ tsp of Violet Colour Gel. If the fondant becomes too sticky add a little more icing sugar to the surface.

-Divide each coloured fondant ball into 12 pieces. Carefully press one ball of each colour together, and lightly kneed together, repeat with all the 12 balls. 
-Roll each piece of fondant into a sausage shape about 5cm long and 2cm thick, this should create a marbled look in the fondant. 
-Pinch the middle of the tail to create an hourglass shape. Use a sharp knife to cut lengthways through one end of the hourglass to create the fin. Gently press down on the fin to flatten out and pinch each end to a point. Smooth the other end of the tail into a cone shape and flatten slightly.
-Insert a cocktail stick into the base of the tail to help it stand in the buttercream.

Decorate the tails, using a sharp knife to score lines on the fin and a straw to add the scales. Using your finger, gently brush the tail with Dr. Oetker Gold Writing Icing for the perfect finishing touch! Allow the tails to set in a cool, dry place for a minimum of 2 hours (ideally overnight) before putting on top of your cupcakes.

Preheat oven to 180⁰C (160⁰C fan over, 350⁰F, gas mark 4). Place the cupcake cases into a 12 hole muffin tray.

Place the margarine in a bowl with caster sugar, eggs and vanilla extract. Sift the flour on top and gently whisk until all the ingredients are mixed well.

Divide the mixture between the cupcake cases and bake for 20 – 25 minutes until risen and lightly golden. Transfer to a wire rack to cool completely.

Lightly beat the butter in a bowl until softened. Gradually add the icing sugar and mix well.

Add the vanilla extract and beat the buttercream until soft and whipped to a good piping consistency.

Divide the buttercream equally between two bowls, add approx. 1tsp of Blue Colour Gel to one bowl of icing, add approx. ½ tsp Violet Colour Gel to the other bowl of icing and mix thoroughly.

Fit a piping bag with a 1cm star nozzle. Using a spatula spread the blue buttercream up one side of the bag so it fills half the piping bag. Repeat for the violet buttercream filling the other half of the piping bag

To pipe the buttercream swirl, start in the centre of the cupcake and pipe round the cupcake until it is covered, then continue to pipe round to build up the swirl on top of the cupcake

Place the sprinkles onto the buttercream to decorate your cupcakes. Use your mermaid tails to finish 12 of your cupcakes.