How to introduce chocolate into all kinds of pastry.
AT CHRISTMAS AND ON NEW YEAR’S EVE, chocolate is obligatory. But in what form? Chocolate puff pastry, perhaps? Chocoholics know that chocolate contains cocoa butter, and they would like nothing better than to be able to substitute it for ordinary butter in puff pastry. But they also know that the hardness of chocolate stands in their way. A few simple observations about state transitions will make it possible to solve this problem and to adapt the majority of classic recipes for pastry to new uses.
To make puff pastry one first makes a paste by kneading flour with a little water, sometimes butter. Next one rolls out the dough and places a layer of softened butter over it. The edges of the dough are then folded back over the butter so that it is completely covered. This envelope is then folded and rolled out six times, with the result that the dough that finally goes in the oven is composed of hundreds of alternating layers of dough and butter.
How can we incorporate chocolate in the dough? Dark chocolate cannot be used in place of butter, despite its cocoa butter content, because it is too hard. Eighty percent of cocoa butter—the only fatty matter permitted by law in France to be used in making chocolate, although other kinds have been proposed—is composed of three triglycerides, or molecules made up of glycerol (commonly called glycerine). These molecules are associated with three fatty acids: palmitic acid, stearic acid, and oleic acid.
Controlling Fusion
This composition explains the remarkable physical properties of cocoa butter. If cocoa butter were composed of only one sort of molecule it would melt at a fixed temperature, just as frozen water melts at 0°C (32°F) under normal pressure. But because it is formed of several types of molecule, its fusion point extends over a range of temperatures from –7°C (19°F) for some of the triglycerides to 34°C (93°F). Even so, 75% of the constituents of cocoa butter melt between 20°C and 34°C (68°F and 93°F) and almost 50% between 30°C and 34°C (86°F and 93°F). In other words, although chocolate is not a pure body, it is not very far from being one.
This characteristic, which is an advantage in eating chocolate bars, is troublesome for the cook, who generally uses it at temperatures in the neighborhood of only 20°C (68°F), hence the difficulties involved in using it in puff pastry, in particular. Comparing cocoa butter with ordinary butter, a more heterogeneous substance, suggests a way to overcome them: The less pure the chocolate, the more malleable it will be. This isn’t a new idea; cooks have long been accustomed to melting chocolate with butter in order to obtain softer chocolate preparations. Nonetheless, one can take the idea farther by heating a neutral oil and adding chocolate to it. The chocolate mixes perfectly with the oil, which modifies the fusion properties of the chocolate in the desired manner.
Not only does this method enable us to make chocolate puff pastry (another solution, by the way, would have been to add cocoa powder to flour or to ordinary butter), the underlying principle makes it possible to reconfigure recipes for all kinds of desserts.
Make All Desserts with Chocolate
From puff pastry it is but a short step to make both shortcrust pastry (including the basic pie dough used to line meat or fish pies) and sugar crust with chocolate; one has only to replace butter with chocolate whose lipid composition has been changed. Similarly, one could make chocolate savarin dough, chocolate brioche dough, chocolate cream puff dough, almond or chocolate cookie dough, and so on. One might even be tempted to use chocolate in an almond custard: Add almond powder and an alcohol to melted chocolate, and then fold in the crème pâtissière (made by cooking egg yolks, sugar, milk, and flour).
Where the fatty matter used is cream rather than butter, it is the cream that must be replaced by a chocolate preparation. In this case it is not enough to manipulate the melting point of the chocolate, for cream is above all an emulsion, a dispersion of fatty droplets in water (from the milk). The droplets remain separated from one another for a long time, though not indefinitely, because they are surrounded by tensioactive molecules, one part of which is hydrophilic (immersed in the water) and another part hydrophobic (immersed in the oil). To replace the cream you will have to make a chocolate emulsion, which is not difficult. In a pan, heat water or a watery solution (coffee, tea, Cognac) together with squares of chocolate. The resulting “chocolate béarnaise” is chemically the equivalent of cream.
Finally, to make a chocolate bavarois (Bavarian cream), a new procedure is necessary. We begin by following the classic recipe to make a crème anglaise: Whisk powdered sugar and egg yolks together, add milk to the mixture, and cook it, then dissolve gelatin in the custard and fold in whipped cream. The problem is how to incorporate the chocolate. It cannot be substituted for the egg yolks, for it is their coagulation that gives the crème anglaise its texture, as particles of the cooked egg are suspended in the water of the milk. Nor can it be substituted for the gelatin.
How about replacing the cream with chocolate? No; the recipe calls for whipped cream. Forget the recipe! Whip up an emulsion of chocolate instead, just as we did in the last chapter to make our Chantilly chocolate, and add this mousse to the final preparation.