Orange Mousse — a light citrus mousse with Grand Marnier

i. Origin & history

Oranges have been prized in French cooking since the late Middle Ages, when bitter Seville oranges arrived from Spain and were used in sauces, preserves and sweets. Sweet oranges became widely available in the seventeenth and eighteenth centuries, and the royal orangeries built to grow them — most famously at Versailles — show how fashionable they were. Orange-flavoured creams, jellies and custards became a standard part of French dessert making.

Orange liqueurs gave the flavour a new dimension in the nineteenth century. Cointreau was created in Angers in the 1870s, and Grand Marnier — a blend of Cognac and bitter orange essence — was created in 1880 by Louis-Alexandre Marnier-Lapostolle. Both became essential ingredients in French pastry and restaurant desserts, from crêpes Suzette to the Grand Marnier soufflé.

The orange mousse grew out of this tradition. Cold mousses lightened with whipped cream and set with gelatine became popular in French and wider European restaurant cooking in the twentieth century, as reliable refrigeration made chilled desserts easy to prepare ahead. Orange mousse, often served in glasses or set in moulds and decorated with orange segments, became a staple of bistro and dinner-party menus, a lighter partner to the dark mousse au chocolat.

Today it is also a common component of modern French pâtisserie, where orange mousse layers are paired with chocolate, almond and caramel in entremets.

ii. Getting real orange flavour into a mousse

Orange juice is mostly water and only mildly acidic, and a mousse dilutes it further with cream. Simply stirring juice into whipped cream gives a pale, faintly flavoured dessert that will not set. Three techniques fix this.

First, reduce the juice. Simmering fresh orange juice by half concentrates its sugars, acids and flavour and removes water that would otherwise thin the mousse. Second, use plenty of zest: the most aromatic part of the orange is the oil in its peel, not its juice, and rubbing the zest into the sugar releases those oils into the base. A little lemon juice restores the brightness that cooking softens. Third, the Grand Marnier adds a deep, bitter-orange and Cognac note that rounds out the fresh fruit.

The base is made like a light curd or sabayon: egg yolks and sugar are whisked with the reduced juice and cooked gently to about 82 °C, until thick enough to coat a spoon. Cooking the yolks makes the mousse safe and gives it body and richness. Gelatine is dissolved in the warm custard to provide the set — fruit mousses have no chocolate to firm them, so gelatine does all the work.

Finally the base is cooled until it is just beginning to thicken and set, then folded into softly whipped cream. If the base is too warm, it melts the cream; if it has already set, it turns lumpy and cannot be folded smoothly. Catching it at the moment it feels cool and syrupy is the key to a smooth, airy mousse.

iii. Ingredients

Makes 6 servings · scroll the side panel to adjust

• 300 ml fresh orange juice (about 4 oranges)
• 2 oranges, finely grated zest
• 1 tbsp lemon juice
• 80 g caster sugar
• 3 egg yolks
• 5 g leaf gelatine (2½ sheets)
• 2 tbsp Grand Marnier or Cointreau
• 300 ml double cream, well chilled
• 2 oranges, segmented, to serve

Use freshly squeezed orange juice; cartoned juice lacks aroma and is often too sweet. Blood oranges in winter give a beautiful pink mousse, and a little Seville orange juice adds a bitter edge. Unwaxed oranges are best for zesting; otherwise scrub them in hot water. Grand Marnier gives a deeper, Cognac-backed flavour; Cointreau is lighter and cleaner. For an alcohol-free mousse, replace the liqueur with extra orange juice and a few drops of orange-flower water. Use agar-agar instead of gelatine for a vegetarian version, boiling it briefly in the juice.

iv. Method

1. Soak the gelatine in cold water for 5 minutes. Simmer the orange juice in a small pan for 8–10 minutes until reduced to about 150 ml. Add the lemon juice.
2. Rub the orange zest into the sugar with your fingertips until fragrant. Whisk in the egg yolks, then the warm reduced juice.
3. Return to the pan and cook over a low heat, stirring constantly, until the mixture thickens and coats the back of a spoon, about 82 °C. Do not let it boil.
4. Remove from the heat, stir in the squeezed gelatine until dissolved, then the Grand Marnier. Strain into a bowl.
5. Cool, stirring occasionally, until the mixture is cool to the touch and just beginning to thicken — about 20 minutes at room temperature, or a few minutes over a bowl of iced water.
6. Whip the cream to soft peaks. Fold a third into the orange base to loosen it, then gently fold in the rest until smooth.
7. Divide between six glasses or ramekins and chill for at least 3 hours, until set.
8. Serve topped with fresh orange segments and a little extra zest.

v. Tips & common mistakes

• Reduce the juice. It is the difference between a mousse that tastes of orange and one that tastes of cream.
• Zest before juicing. And take only the coloured outer peel; the white pith is bitter.
• Cook the custard gently. Boiling scrambles the yolks. Strain it if any curds form.
• Catch the setting point. Fold in the cream when the base is cool and syrupy. If it sets too far, warm it very briefly over hot water and stir until smooth.
• Whip the cream softly. Soft peaks fold in easily and give the lightest texture.
• Segment the oranges properly. Cutting segments free of membrane gives a neat, juicy garnish without chewy pith.

vi. Variations

A chocolate-orange mousse layers this mousse over a thin layer of dark chocolate mousse or ganache in the glass. A blood orange mousse uses blood orange juice for a pink colour. Swap the oranges for mandarins, clementines or passion fruit, or add a little grated fresh ginger. Set the mousse in a ring on a sponge or biscuit base to make a simple orange mousse cake.

Other citrus desserts on DessertCat include the tangerine tart, the British lemon posset and the lemon meringue pie. For more mousses, see the white chocolate mousse and the hazelnut mousse, and for orange in a hot dessert, the berry soufflé page explains the fruit soufflé method that also suits orange.

vii. Serving & storage

Serve the mousse well chilled in glasses, topped with fresh orange segments, a few strands of candied peel or some grated dark chocolate, with a crisp biscuit such as a tuile, a langue de chat or shortbread alongside. It is a refreshing end to a rich winter meal, when citrus is at its best.

Keep the mousse covered in the fridge for up to 2 days; add the orange segments just before serving. It can be frozen for up to a month and served semi-frozen, like a parfait, after 10 minutes at room temperature. The reduced juice and orange custard base can be made a day ahead, but warm and cool it again to the setting point before folding in the cream.

ix. More from French

• Tangerine Tart — winter citrus tart
• White Chocolate Mousse — silky and pale
• Hazelnut Mousse — praline mousse
• Berry Soufflé — hot fruit soufflé
• Lemon Posset — British set lemon cream
• Jaffa Cakes — orange and chocolate