Under the sea mermaid cake

1/2 Mermaid tail scales, mini clams and ruffled wave-effect icing stack up to marvellous marine effect in this double-decker under the sea mermaid cake.

Brought to you by Lakeland

This is one centrepiece that’s really dressed to impress!

Shared with us by Lakeland, this tutorial will have you creating your own mermaid cake summer party masterpiece in no time at all. Enjoy!

TOP TIP: To make the coloured icing, add the stated amount of Wilton® Colour Right System icing colourings to Renshaw Ready to Roll White Icing. (Please note: you’ll need a total of 2.6kg (5lb 8oz) icing to make this recipe.)


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You will need

For the cake:

  • 12cm (4 1/2 in) deep round cakes: 20cm (8in) and 15cm (6in)

To decorate:

  • 300g (10 1/2 oz) Renshaw Ready to Roll White Icing plus 1 tsp Tylo powder, to cover the cake board
  • 1.5kg (3lb 3oz) Renshaw Ready to Roll White Icing, to cover both cakes
  • Wilton® Colour Right System icing colourings: blue, brown, red, yellow

For the blue waves on the bottom tier:

  • 250g (9oz) blue icing (5 drops blue, 2ó drops brown)
  • 150g (5 1/2 oz) white icing
  • 1 tsp Tylo powder

For fish scales on the top tier:

  • 100g (3 1/2 oz) light pink icing (end of cocktail stick dipped in red)
  • 100g (3 1/2 oz) dark pink icing (2 drops red)
  • 100g (3 1/2 oz) jade green icing (2 drops blue, 1 drop yellow – mixed in a small pot with most, not all of the colouring added to the icing)
  • 100g (3 1/2 oz) lilac icing (3 drops red, 1 drop blue – mixed in a small pot with only a quarter added to the icing)
  • Under the Sea Sprinkletti Mix or Unicorn Sprinkletti Mix
  • Edible glitter dust, silver (optional)

For the clamshell:

  • 1 free-range egg white, approximately 35g (1.oz) in weight
  • Caster sugar, twice the weight of the egg white, approximately 70g (21/2 oz)
  • Edible glitter dust, silver


  • Pizza wheel
  • Cocktail stick
  • Decorating brush
  • Baking parchment
  • Disposable piping bag


A day or two before your undersea party, prepare the cake board. Mix 300g (10 1/2 oz) of Ready to Roll White Icing with 1 tsp of Tylo powder. Roll out and completely cover a 30cm (12in) round cake board. Allow the icing to harden.
Make the cake sponges to a favourite recipe of your own choice – you will need one 20cm (8in) and one 15cm (6in) cake, both about 12cm (4 1/2 in) deep.
Roll out Ready to Roll White Icing and cover both cake tiers separately.

To make the waves:

To make the ‘waves’ on the bottom tier, take the blue icing and the white icing and divide to make 4 ombre shades, from palest to darkest blue, as follows: 25g (1oz) blue + 75g (2 1/2 oz) white (palest) 50g (1 1/2 oz) blue + 50g (11/2 oz) white 75g (21/2 oz) blue + 25g (1oz) white 100g (31/2 oz) blue (darkest)
Knead the blue and white icings together so you have 4 balls of varying shades of blue. To each ball, add 1/2 tsp of Tylo powder and knead in well until the icing feels elastic.
Starting with the palest blue coloured icing, shape into a sausage 10cm (4in) long. Roll the sausage out into a long thin strip approx. 50cm (19 1/2 in) long and 7-8cm (2 1/2-3 1/2 in) wide. The addition of the Tylo powder means that the icing will have strength and elasticity so you can roll it out thinly – approx. 2mm (1/16in) and it will be more resistant to tearing when you handle it.
Using a pizza wheel, trim a straight edge on one side of the first strip and cut the other edge in a random wavy line.
Dip a clean decorating brush into cooled boiled water and paint a ring of water 5cm (2in) down from the top of the 20cm (8in) round cake.
Wrap the strip around the cake, pressing along the bottom straight edge to secure it to the cake. Use your fingertips to gently roll the top, wavy edge of the strip outwards and downwards to give it shape.
Repeat steps 2 and 3 for the next palest shade of blue icing, then use water to attach this to your cake about 2.5cm (1in) below the palest strip. Repeat for the third strip. With the last strip, ensure that the straight edge is around the very base of the cake, touching the cake board.

Add the pearls:

Separate out some large blue pearls from the Unicorn Sprinkletti Mix, or some white pearls from the Under the Sea Sprinkletti Mix, and stick to the waves with a little edible glue.

Make the scales:

For the scales on the top tier, roll out each of the 4 colours of icing (light pink, dark pink, jade green and lilac) until 2mm (1/16in) thick.
Use the larger cutter from the Small Easy Rose Cutter Set to cut out lots of icing shapes. Cut the shapes in half lengthways using the pizza wheel and divide the strips into ‘scales’ of pairs and trios.
Starting at the bottom of the 15cm (6in) cake, wrap a 1cm (®ˆin) strip of (any) coloured icing around the base of the cake – this will help to hide the join between the tiers.
Brush the back of each ‘scale’ with water as you attach them to the cake, starting at the base and completing one layer around the circumference of the cake before moving upwards to the next layer. Ensure that you stagger and overlap the rows so that there are no gaps showing.
Continue working your way up the cake and over the top edge, then cover the top of the cake with concentric circles of the scales. If desired, finish with a spray of silver edible glitter dust. Carefully place this top tier on top of the bottom tier.

Make the clamshells:

To make the clamshell on top of the cake, whisk up the egg white until it forms stiff peaks. With the whisk still going, add the sugar a teaspoon at a time until it is all incorporated and the meringue mix is thick and glossy. Use a cocktail stick dipped in the Wilton blue icing colour to tint the meringue a delicate shade of pale blue.
Line a baking sheet with baking parchment. Put the meringue into a disposable piping bag and cut off the end to make a hole approx. 1cm (1/2 in) across.
Pipe two clamshell shapes from the meringue mixture in a fan shape approximately 10x10cm (4x4in). Pipe one central straight line, tapering it towards the bottom, then pipe three lines on either side of this, also tapering and gradually getting shorter in the fan shape.
Put the meringues in the oven at a low heat (about 80˚C/Gas Mark ®˘) to dry out for 2 hours or overnight. Leave them in the oven to go cold.
Sandwich the clamshells together with 2 tbsp of buttercream and add a large pea-sized ball of fondant icing for the pearl. Spray with silver glitter dust and attach to the top of the cake with a blob of royal icing.
Last updated 10 months ago

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