HomeRecipesRhubarb and Custard Sphere by Michael Coggan

Rhubarb and Custard Sphere by Michael Coggan

(This recipe appeared in the Spring 2022 issue of Pastry Arts Magazine)

As a child I loved rhubarb and custard flavored candies, so this dessert, which features the flavors rhubarb, vanilla and orange, evokes a certain nostalgia for me. The sourness of the rhubarb and the rich creamy flavor of the custard is a personal favorite of mine.

Yield: 24 servings

Rhubarb Purée

  • 1.5 kg rhubarb, trimmed and prepped
  • 400 g super-fine granulated sugar
  1. Cut the rhubarb into roughly 1ʺ (2.5 cm) batons and place on sheet pan. Sprinkle the sugar over the rhubarb and toss well, making sure it is all coated. Cover the tray completely in plastic wrap, making sure it is airtight. Place in a steamer and steam for 30 minutes, or until the rhubarb is completely soft.
  1. Remove from the oven and strain the excess juice from the rhubarb through a sieve. Save this juice – you will use it later for another component of the dessert.
  1. Place the soft-cooked rhubarb in a Thermomix or blender and blend to a smooth purée. Set this aside for the rhubarb mousse.

Vanilla Custard

  • 1000 g double cream (48% butterfat)
  • 210 g super-fine granulated sugar
  • 1 vanilla bean, split and scraped
  • 240 g egg yolks
  1. Preheat oven to 248˚F (120˚C).
  1. Place the double cream, sugar and scraped vanilla bean in a heavy-bottomed saucepan and place over medium-high heat. Put the egg yolks in a bowl. Bring the cream, sugar and vanilla to a boil, then pour over the egg yolk and mix with a spatula. Return the mixture to the saucepan and cook over low heat, stirring constantly, until it thickens slightly. Remove the pan from the heat and cool in an ice bath (or blast-chill, if possible).
  1. Place Silikomart petit four mold #Sf027 on a tray that is deep enough to accommodate some water for baking. Once the custard mix has cooled, pour 0.67 liq oz (20 ml) of it into each mold and then pour some hot water in the tray, letting it go halfway up the sides of the molds. Bake for 20 minutes, or until the custard is set, with a slight wobble. Cool slightly, then place on a clean, dry tray and place in the blast freezer or regular freezer for a few hours until completely frozen. You should be able to pop them out of the molds.

Rhubarb Compote

  • 400 g rhubarb, trimmed
  • 490 g reserved rhubarb juice
  • 40 g liquid glucose
  • 100 g super-fine granulated sugar
  • 24 g pectin NH
  1. Make 3 vertical and horizontal cuts in the trimmed rhubarb stalks, then cut them into a fine brunoise. Place in a bowl and set aside.
  1. Place the rhubarb juice and liquid glucose in a pan over medium heat and bring to 104˚F (40˚C).
  1. Place the sugar and pectin NH in a bowl and mix together thoroughly, then whisk into the rhubarb juice when it comes to 104˚F (40˚C). Turn the heat up slightly and bring the mixture to the boil, then allow to boil for about 1 minute. Add the rhubarb brunoise, lower the heat slightly so the mixture simmers, and cook for 2 minutes. Remove from heat, transfer to clean bowl and cool slightly.
  1. Using the same molds as for the custard, pipe or spoon 20g of the compote into each of the molds. Place the molds in a freezer or blast-freezer and allow to chill until they are set hard and you are able to pop the compote out of the molds.

Orange Cake

  • 250 g unsalted butter, softened
  • 210 g super-fine granulated sugar
  • Finely grated zest of 2 oranges
  • 250 g whole eggs
  • 250 g all-purpose flour
  • 15 g baking powder
  1. Preheat the oven to 338˚F (170˚C).
  1. Place the softened butter, sugar and orange zest in the bowl of an electric mixer fitted with the paddle and cream until pale and fluffy. Gradually add half of the eggs, mixing well, then add the flour and baking powder and mix until blended. Add the remaining eggs and give one final mix until light and fluffy.
  1. Spread the batter onto a silicone baking mat to roughly 0.3ʺ (8 mm) in thickness and bake for 12-14 minutes.

Soaking Syrup

  • 150 g super-fine granulated sugar
  • 100 g water
  • Juice from 2 oranges
  1. Place all of the ingredients into a pan over high heat and bring to the boil. Allow to boil for about 2 minutes, or until the syrup thickens slightly.
  1. When the cake comes out of the oven and while it’s still hot, brush on the hot syrup over it, making sure to coat the sponge evenly. Let the sponge cool completely, then, using a 1.5ʺ (4 cm) pastry cutter, cut out disks of the sponge.

Rhubarb Mousse

  • 6 sheets gelatin (bronze)
  • 525 g double cream
  • 150 g mascarpone cheese
  • 600 g Rhubarb Purée (from above), divided
  1. Bloom the gelatin in cold water.
  1. Place the double cream and mascarpone in the bowl of an electric mixer fitted with the whisk attachment and semi-whip to the ribbon stage, so that it is not really holding a peak.
  1. Place 150 g of the Rhubarb Purée in a pan and heat up, then add the drained gelatin and stir until gelatin is completely melted. Add the warm purée to the remaining 450 g purée in a bowl. Fold the mascarpone mixture into the purée mixture. Transfer to a pastry bag.

Begin Assembly

  1. Pipe the Rhubarb Mousse into the bottom half of a Silkomart 2-piece sphere mold, filling it halfway.
  1. Remove the Rhubarb Compote and the set custard from the freezer, sandwich them together and place in the center of the mold, on top of the mousse, with the compote facing down. Place a piece of the Orange Cake on top of the custard.
  1. Place the second part of the mold on top and make sure it is properly secured. Pipe the remaining mousse through the hole in the top of the mold, encasing the inserts of compote, set custard and cake in the Rhubarb Mousse. Flatten off the mousse at the hole at the top of the mold.
  1. Place the molds into the blast-freezer or freezer and allow to freeze completely, until they can be popped out of the molds cleanly. Freeze until ready to glaze and finish.


  • 8 sheets gelatin (bronze)
  • 320 g water
  • 160 g super-fine granulated sugar
  • 320 g liquid glucose
  • 210 g double cream
  • 750 g white chocolate
  • Pink food coloring
  1. Bloom the gelatin in cold water.
  1. Place the water, sugar and glucose in a pan over medium-high heat and bring to the boil. Continue to boil until syrup reaches 223˚F (106˚C). Remove from the heat and add the drained gelatin, mixing until dissolved. Stir in the cream.
  1. Place the white chocolate in a bowl and pour the syrup over it. Use an immersion blender to emulsify. Add a little bit of pink coloring and blend again, adding more color as necessary to get the color you want. Use at 93˚F (34˚C).

Ruby Chocolate Dip

  • 600 g Ruby chocolate
  • 400 g cocoa butter
  1. Place both ingredients in a bowl over a bain marie and heat, stirring frequently, until completed melted and combined. Place the bowl aside and allow to cool slightly.


  • 410 g all-purpose flour
  • 140 g confectioners’ sugar
  • 6 g salt
  • 180 g unsalted butter
  • 2 whole eggs
  1. Place the flour, confectioners’ sugar, salt and butter in the bowl of an electric mixer fitted with the paddle attachment and mix at low speed. Mix to a sandy, breadcrumb-like texture.
  1. Add the eggs and mix until the dough starts to come together. Remove from bowl and shape into a disc. Wrap in plastic and refrigerate for at least 30 minutes.
  1. Roll the dough out to a thickness of 0.16ʺ (4 mm), then use a fluted 1.5ʺ (4 cm) round cutter to cut out discs from the dough. Place in between 2 perforated silicone mats and bake at 329˚F (165˚C) for 10 minutes, or until golden brown.

Ruby Chocolate Flowers

  • 400 g Ruby chocolate
  1. Temper the chocolate and spread over a flower stencil (I make my own using 0.5 mm UV clear PVC and a flower craft punch). Allow to set.

Final Assembly

  • Freeze-dried raspberries
  1. Remove the mousse spheres from the molds and, while still frozen, place on a cooling rack over a tray. Ladle the glaçage on the top of the spheres (you can give them a second coat, if necessary). Place a skewer in the top of each sphere and pick up by the skewer, trying to wipe off any excess drips of the glaçage at the bottom. Dip the sphere halfway into the Ruby Chocolate Dip, allowing the excess to drip off. Wipe the bottom of the sphere onto some grease-proof paper, then set it down and let it set completely (this will make them easier to handle, as you can pick them up from the chocolate-dipped bottom).
  1. Using a paper cone of melted chocolate, stick the sablè to a gold patisserie board, then add another spot of white chocolate on top of the sablè and place the rhubarb sphere on top. Arrange 3 of the Ruby Chocolate Flowers on top of the sphere and then place some single cells of the freeze-dried raspberries around the top of the sphere.

About Michael Coggan

Michael Coggan is the Head Pastry Chef of Pettigrew Bakeries in Cardiff, U.K. He described his style as modern British, although he uses lots of French technique because he was classically trained. He adapts his recipes to bring back memories.

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