Because dinner needs to be special, you decide to buy one of the widely featured dark varieties of chocolate that have a high percentage of cocoa, and don't come cheap, such as Lindt 70 per cent extra-fin, or Green and Black's organic dark chocolate. Given that a rich chocolate pudding needs 400-500g of chocolate, such puddings can prove expensive.
It was after a similar, real-life chocolate experience that I set about testing chocolate mousse and chocolate cake, using different makes of dark chocolate. In the mousse test there were four brands:
Lindt 70 per cent cocoa extra-fin: cocoa mass, sugar, cocoa butter, emulsifier (lecithin), vanilla, 70 per cent minimum cocoa solids. 99p for 100g.
Green and Black's dark organic chocolate: cocoa beans, sugar 29 per cent, soya, lecithin, vanilla 0.1 per cent, 70 per cent minimum cocoa solids. pounds 1.35 for 100g.
Menier: cocoa mass, sugar, cocoa butter, soya, lecithin, vanilla extract, 52 per cent minimum cocoa solids. 74p for 100g.
Cadbury's Bournville: sugar, cocoa mass, vegetable fat, butterfat, cocoa butter, soya, lecithin, 36 per cent minimum cocoa solids. 50p for 100g.
The assembled tasters were all "lay" chocolate lovers and their first task was to form an opinion of the chocolate in its raw state. Lindt won hands down as an eating chocolate, with its lovely smooth texture and pleasant acidity. Green and Black's came next for flavour, but the finish was rough and rather powdery. Then came Menier: good texture, but a little on the sweet side, and lacking in cocoa. Poor old Bournville, I'm afraid, bore little resemblance to anything decent.
On to the mousse. The first step was to break up and melt the chocolate in a bowl over simmering water. This part was fine: each one melted down to a smooth, rich river. Next the eggs were separated, and the whites whisked until they were stiff, while the egg yolks were beaten into the melted chocolate.
And here the trouble began, as the different makes of chocolate behaved in radically different fashions. If there is a rule of thumb, it is that the more cocoa chocolate contains, the more the mixture seizes up; when this was the case, it proved a struggle to incorporate the egg whites, and the resulting mixture was very dense.
The Lindt mousse, which promised to be the creme de la creme of the set, seized up at the egg yolk stage; the result was absurdly heavy and truffle-like. Tasters ruled it out.
Green and Black's organic chocolate, also high in cocoa, reacted in the same fashion, producing a solid mousse that was not sweet enough. This scored lowest of all.
Then there was Menier. For many years, until we got excited about real chocolate, this was the darkest of the darks, a top-class cooking chocolate that you would likely dip into as an eating chocolate if you were inclined that way. Things began to look moussier with Menier: it had a much better texture than the former two mousses, and though it couldn't beat Lindt in the cocoa class, it still produced the best result so far.
And Bournville, scorned as an eating chocolate, was the one that responded with most grace to the addition of egg yolks. It was miles ahead of the others in terms of texture, really gloopy and pitted, with 30 per cent more volume - the downside was that it was hideously sweet, and tasted of low-grade cocoa.
The results were a compromise: either texture and no taste, or taste and no texture. But we eventually agreed that Menier made the best mousse, followed by Bournville, then Lindt and finally Green and Black's.
And what about chocolate cake? Could it be the same story here? Out came the food processor, and I assembled just two cakes for comparison, one made with Bournville and one with Lindt extra-fin.
Following on from the strange results of the mousse experiment, I was expecting Bournville to win the cake competition. But it didn't. Lindt produced the best texture of cake; it was deliciously, deeply chocolaty. The Bournville cake was perfectly acceptable, but a touch on the sweet side, and it sank more as it came out of the oven.
The moral of the story is to remember that chocolate is a composite product, and therefore behaves differently in different recipes depending on the brand you use, and the proportions of the ingredients that make it up.
Premium, cocoa-rich chocolate, which is usually low in sugar, makes delectable chocolate sauces, icings, even sorbet, and, according to my recipe, a very good cake. But it is not good material for a mousse, where half the point is texture.
Now some bright spark will write in, asking if I had thought of blending them? Yes, I had. That could be the mousse of tomorrow.
Chocolate mousse, serves 4
250g/9oz dark chocolate
5 egg yolks (size 2)
1 tbsp dark rum or brandy
6 egg whites (size 2)
Melt the chocolate in the top half of a double boiler, or a bowl set over simmering water. Incorporate the egg yolks and then the alcohol. Whisk the egg whites until they are stiff, and then incorporate the rest as lightly as possible. Pour into a bowl, or individual bowls, and chill for several hours.
Chocolate cake, makes 1 x 20.5cm/8in cake
225g/8oz dark chocolate
175g/6oz unsalted butter
4 eggs (size 2), separated
175g/6oz caster sugar, plus 1 tbsp
4 tbsp strong black coffee
55g/2oz plain flour, sifted
1 heaped tsp baking powder, sifted
for the chocolate glaze
225g/8oz dark chocolate
55g/2oz unsalted butter
2 tbsp coffee or brandy
Preheat the oven to 170C (fan oven)/180C (electric oven)/350F/gas mark 4.
Melt chocolate and butter together in the top half of a double boiler, or in a bowl set over simmering water. Either by hand or in a food processor (with multipurpose blade), whisk egg yolks and sugar together until they are pale and thick. Add chocolate and coffee, and mix in flour and baking powder.
Whisk the egg whites until they are stiff, sprinkle over the remaining tablespoon of sugar and continue whisking until glossy. Incorporate the egg whites into the cake mixture as deftly as possible. If using a food processor, a quick burst at high speed will do.
Butter a 20.5cm/8in cake tin with a removable base. Pour the cake mixture into the tin, and give it several sharp taps on the work surface to eliminate any air pockets. Cook the cake for 55 minutes. Loosen the collar and allow the cake to cool.
Invert the cake before icing it, to achieve a totally flat surface. Melt half the chocolate and butter over a low heat. Add a tablespoon of coffee or brandy. Coat the top and sides of the cake, using a palette knife. Allow to set, then repeat the process using the remaining ingredients. For a special occasion you can employ chocolate curls and swirls, or surround the cake with white flowers