Classic chocolate mousse in a bitter chocolate casing

Like fine wines, chocolates from different parts of the world have different flavours, so we've asked chocolate connoisseur Willie Harcourt-Cooze for some expert tips on identifying the best type of choc for different recipes, like this indulgent dessert.

Willie says: This is one of my dinner party favourites, and the chocolate case adds a bit of flair to the presentation. I’ve used two very different chocolates here: the Indonesian Javan is light coloured, with hints of caramel and toffee flavours, while the Madagascan Sambirano is deep and dark, with subtle notes of summer berries.

Serves 12

Ingredients250g Madagascan Sambirano Superior 71% chocolate, roughly chopped300g Indonesian Javan Light Breaking 69% chocolate, roughly chopped6 eggs, separated80g caster sugar450ml double cream, lightly whippedEquipment: 26-cm tart or shallow cake tin

Method1. Lightly oil the tart or cake tin, then take a piece of baking paper, at least 45 x 45 cm, and press it into the tin so it sticks firmly to the base and sides and comes up a little above the rim of the tin.2. Melt the Madagascan Sambirano chocolate in a heatproof bowl set over a pan of gently simmering water, making sure the bottom of the bowl is not in contact with the water. Pour into the lined tin and spread evenly, with a flexible spatula, over the bottom and up the sides. Chill in the fridge.3. Melt the Indonesian Javan chocolate in a heatproof bowl set over a pan of gently simmering water, making sure the bottom of the bowl is not in contact with the water. In a separate bowl, whisk the egg whites with half the sugar until stiff.4. In another bowl, whisk the egg yolks with the remaining sugar and stir into the melted chocolate. Fold in the lightly whipped cream, then fold in the egg whites. Tip the mixture into the prepared chocolate case and place in the fridge to chill for at least 2 hours, preferably overnight.5. Carefully lift out of the tin and peel the baking paper off the sides. Use a fish slice or spatula to lift off the baking paper on the base and place on a serving plate. Keep chilled until ready to eat and serve with whipped cream or crème fraîche.

Willie's chocolate guideVenezuelan 72%, Willie's Cacao - Very dark flavour with nutty and coffee tonesPapua New Guinea 64%, Montezuma's - Smoky tobacco flavour with hints of vanillaEquador 70%, Amedei - Nutty with a slight fruitiness

Thanks to The Candy Company for our sweet trees

Try Willie's after-dinner liqueur: sloe chocolate vodka

Get Phil Vickery's recipe for the Queen of Puddings made with raspberry jam

Catch up with the last seven days of This Morning on ITV Player