20cm Rhubarb & Custard Celebration Cake

Made for our 50th Anniversary celebrations in 2 of our 20cm Loose-Based Cake Tins

Ingredients

Rhubarb Cake

  • 185g unsalted butter, softened, plus extra to grease
  • 220g caster sugar
  • 3 large eggs
  • 325g self-raising flour
  • 185ml milk
  • 10 drops Natural Rhubarb Flavour
  • A few drops of Wilton Pink/Rosa Gel Icing Colour

Custard Cake

  • 185g unsalted butter, softened
  • 220g caster sugar
  • 3 large eggs
  • 325g self-raising flour
  • 185ml milk
  • 10 drops Natural Custard Flavour

Custard Frosting

  • 500g icing sugar, sifted
  • 10 drops Natural Custard Flavour
  • 160g unsalted butter, softened
  • 50ml milk, gently warmed

Rhubarb Frosting

  • 500g icing sugar, sifted
  • 10 drops Natural Custard Flavour
  • 160g unsalted butter, softened
  • 50ml milk, gently warmed
  • A few drops of Wilton Pink/Rosa Gel Icing Colour

Chocolate Button Macarons’ (Makes 30 chocolate macarons’ (60 chocolate buttons)

  • 400g white chocolate, broken up
  • Rhubarb frosting, reserved from the cake recipe

Custard Number Cookies – Makes 20 (please note ─ only 2 are required for the cake)

  • 175g unsalted butter, softened 
  • 200g caster sugar
  • 1 egg
  • 6-8 drops Natural Custard Flavour
  • 1 tsp baking powder
  • 275g plain flour, plus extra to dust
  • 55g custard powder
  • Pinch salt

Icing to decorate cookies – note : enough to decorate the two cookies for the cake, but can easily be multiplied.

  • 30g ready-to-roll white icing
  • A little edible gold lustre powder
  • White shimmer pearls

Instructions

Make the cakes

  1. Grease the cake tins and line the bases with baking parchment. Preheat the oven to 160°C/310°F.
  2. Begin by making the rhubarb cake. Using an electric mixer, beat the butter and sugar together until light and fluffy. Add the eggs one at a time, adding a spoonful of flour with each to stop the mix curdling.
  3. Add half the milk and half the remaining flour and mix well. Add the remaining milk and flour and the flavour. Using a cocktail stick, add a few drops of the Gel Icing Colour and mix everything together until smooth. Add more colour a little at a time, mixing between each addition, until your desired shade is reached.
  4. Transfer the mixture into one of the cake tins and use a spatula to make a large dip in the middle (so the mixture is about twice as deep at the edges) ─ this will help to achieve a level top.
  5. Bake for 55 minutes ─ when ready, the middle of the cake should be firm to the touch, and a skewer inserted into the middle should come out clean. Cool in the tin for 15 minutes, carefully remove the cake, place on a wire rack and leave until completely cold.
  6. While the rhubarb cake is in the oven, begin making the custard cake. Follow steps 2-5 above, omitting the Gel Icing Colour.

Make the frosting

  1. While the second cake is cooling, make the custard frosting. Place the icing sugar, flavour, butter and milk in a large bowl and, using an electric mixer, mix on a low speed until combined and smooth.
  2. To make the rhubarb frosting, follow the step above for the custard frosting when combined, use a cocktail stick to add a few drops of the Gel Icing Colour at a time, mixing between each addition, until your desired shade is reached. Transfer 1½ tablespoons of the pink rhubarb frosting to a bowl, cover with clingfilm and reserve ─ this will be used to fill the chocolate button macaroons’ and attach the number cookies later .

Decorate the cake

  1. Remove the baking parchment from the cold cakes. Check the tops of the cakes are level ─ if not, remove any peaks with a sharp knife. Using a long, sharp knife, half each cake so you end up with 4 thin cakes.
  2. On a cake stand, stack the sponge layers, starting with a pink layer, spreading ⅓ of the custard frosting between each layer.
  3. Use ⅓ of the rhubarb frosting to put a thin layer on the sides and top of the cake, sealing any loose crumb and filling the gaps between the layers so you get a smooth top and sides ─ leave to dry completely. Cover the remaining frosting with clingfilm and reserve.
  4. Once the cake is dry, use the remaining ⅔ of rhubarb frosting to cover the top and sides of the cake, using a metal spatula, dipped in hot water and drained of excess water, to smooth the icing. Use a clean cloth to wipe any excess frosting from the cake stand.

Tip: If desired, decorate with Chocolate Button Macarons’ and Custard Number Cookies.

Chocolate Button Macarons’

  1. Place the chocolate into a heatproof bowl set over a pan of boiling water, ensuring the bowl is not in contact with the water. Allow to melt gently, remove the bowl from the pan and stir the chocolate to ensure it is smooth.
  2. Using a teaspoon, fill the wells in the moulds, then place in the fridge for 20 minutes or until set then carefully turn out onto a clean surface. You will have 60 chocolate buttons.
  3. Place a small, round nozzle in a piping bag then fill the bag with the reserved rhubarb frosting. Pipe a small dot of frosting onto one chocolate button and then sandwich together with another button ─ repeat until you have 30 chocolate macarons’. (Remember to save a little frosting to attach the 2 cookies, below.)
  4. Gently push into position around the top edge of your finished cake. We used 23 on our cake (and nibbled the rest!), but you could use all 30 macaroons’. Tip: If you only have one Macaron Chocolate Mat, make the chocolate buttons in batches of 15, re-melting the chocolate between each batch.

Custard Number Cookies

  1. Preheat the oven to 180°C/350°F.
  2. In a large bowl, cream together the butter and sugar until pale and light. Add the egg and the custard flavouring, and then gradually stir in all the dry ingredients until you have a smooth, stiff dough. Wrap the dough in clingfilm and refrigerate for about 15 minutes.
  3. Remove the dough from the fridge, divide the dough into 2 pieces and roll each half between two sheets of baking parchment to about the thickness of a £1 coin.
  4. Using the Numbers Cookie Cutter Set, punch out a 5 cookie and a 0 cookie for the cake. Stamp numbers into the remaining cookies as required. Re-roll the scraps of dough and cut into cookies.
  5. Place the biscuits onto baking sheets lined with parchment and bake for 8-10 minutes until they begin to brown at the edges. Remove from the oven, allow to cool on the baking sheets for a few minutes, then transfer to a wire rack and leave until cold.

Icing to decorate cookies

  1. Roll out the icing and, using the same number cutter as you used for the base biscuits, cut out the icing shapes.
  2. Lightly brush the back of the icing with a little cool, boiled water ─ this will help the icing to stick to the biscuit.
  3. Carefully lay the icing onto the biscuit. Brush with a little gold lustre, and decorate around the edge of the biscuit with the pearls. Then, using a little reserved frosting on the back of the biscuit, attach to the front of the cake.