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Chocolate Truffle (Ganache Rolled in Cocoa)

Name: Chocolate Truffle (Ganache Rolled in Cocoa)
Prep time: 40 min
Cook time: 10 min
Total time: 50 min
Yield: 30 servings
Cuisine: French
Ingredients: 300 g dark chocolate; 150 ml double cream; 30 g butter; 1 pinch salt; 1 tbsp rum or cognac; 1 tsp vanilla extract; 60 g cocoa powder; 300 g dark chocolate

The French confection: hot cream poured onto chocolate, set, rolled and dusted with cocoa. A ganache is an emulsion that sets rather than pours, and nothing was added to hold it — the chocolate's own lecithin and cocoa particles do that. And one number decides what you get from the same operation: 2:1 chocolate to cream gives a truffle you can roll, 1:1 a glaze you pour, 1:2 a sauce.

Ingredients

30servings

The ganache (makes about 30)
dark chocolate · 60-70% cocoa, chopped small300 g
double cream · at least 35% fat150 ml
butter · soft, in at the end30 g
salt1 pinch
Flavouring (optional)
rum or cognac1 tbsp
vanilla extract1 tsp
To coat
cocoa powder · unsweetened60 g
If enrobing instead
dark chocolate · separate, for tempering300 g

Steps

Chop the chocolate small and put it in a bowl. Uneven pieces mean the small ones scorch and seize before the large ones have melted.
⏲ 5 min
Heat the cream just until it begins to boil at the edges and pour it over the chocolate. Then leave it alone for a minute — as poire belle Hélène puts it, stir the moment it lands and the emulsion starts before the chocolate has melted, and it splits.
⏲ 3 min
Stir from the centre, in small circles. Once the middle has come together glossy, widen the circles gradually to pull the rest in. Sweeping the whole bowl from the start never forms the emulsion.
⏲ 5 min
At 35-40°C stir in the butter, the salt, and the spirit if using. It should be one glossy cream — oil standing separate means it has split.
⏲ 3 min
If it has split, add a tablespoon of warm cream and stir again from the centre. It usually comes back (emulsions).
⏲ 3 min
Pour into a shallow dish, press cling film onto the surface and set 3-4 hours at room temperature. In the fridge the outside sets and the middle stays soft.
⏲ 240 min
Scoop 12-15g at a time with a teaspoon or a piping bag onto a tray dusted with cocoa. Handle it briefly — cocoa butter starts melting at body temperature.
⏲ 10 min
Roll each one between your palms in the cocoa. It does not need to be a sphere; the marks of having been rolled by hand are the shape of the thing.
⏲ 10 min
Shake off the excess in a sieve. Airtight at room temperature, a week. In the fridge the surface beads with moisture.
⏲ 5 min

Tips & Variations

Variations

The ratio decides what you get. Chocolate to cream at 2:1 gives a truffle you can roll, 1:1 a glaze you pour, 1:2 a sauce that runs. Same two ingredients, same operation, one number. Poire belle Hélène is the poured version, and Sachertorte fills the same slot with syrup in place of cream.
Enrobed truffles: dipped in tempered chocolate rather than rolled in cocoa. The shell snaps and they keep longer, at the cost of having to temper (see the tips).
Ganache montée: chilled ganache whipped to increase its volume, used as a piping cream.
Flavourings: rum, cognac, Grand Marnier, coffee, cinnamon, Earl Grey, yuzu zest. Two tablespoons of spirit is the ceiling — beyond that the emulsion will not hold.
Not the same as romkugler or Rumkugeln. What is sold in that shape across Denmark and Germany is leftover cake crumb bound with jam and rum, not ganache. Search Commons for truffles and it is mostly those.
The name and the origin: ko.wikipedia records it as a chocolate dessert made in 1895 by Louis Dufour, a pâtissier from Chambéry. The shape and the cocoa dust are meant to look like an earthy truffle, and they are commonly given as a Christmas present.

Tips

A ganache is an emulsion that sets, which is the corner of emulsions and pan sauces this dish is cited in. That guide sorts emulsifiers by what you put into the pan, and keeps a "thick, but not emulsions" section to police the boundary. Nothing was put in here: a ganache is cocoa butter dispersed in the water of the cream, held by chocolate's own lecithin and cocoa particles. And it sets firm enough to roll rather than pour, where the other examples on that list are things you can still tip out of a jug.
Wait a minute, then stir from the centre. Poire belle Hélène gives the same instruction, and the reason is order: start the emulsion while solid chocolate is still sitting there and the fat-to-water ratio is locally wrong, so it splits.
A split ganache can be brought back. This is where it differs from protein setting, as in crème brûlée: protein that has coagulated is finished, an emulsion can be re-formed. A tablespoon of warm cream, stirred again from the centre.
Set it at room temperature. In the fridge the outside firms first and the middle stays soft, and the surface beads when it comes out. There is nothing to be gained by hurrying this step.
Enrobing needs tempering, and that is one step past what nanaimo bar says. That page has it exactly right: cocoa butter "crystallises as it cools. Crystals are hard and they cleave." What this adds is that there is more than one crystal form. Cocoa butter can set in six of them, and only one is hard, snaps and shines. Tempering is bringing melted chocolate down to 31-32°C with seeds of that form still in it; without that it sets in unstable forms, converts over the following days, and pushes fat to the surface as white bloom.
Rolled in cocoa, no tempering is needed at all. The outside is not chocolate, so crystal form never arises. Dufour's original was this version and so is the base recipe here.
Do not handle them for long. Cocoa butter starts to melt near body temperature, so a long roll between the palms leaves the surface greasy and the cocoa clumped. If your hands are warm, cool them under the tap partway through.