Pastillage is one of the major decorative elements used by professional pastry chefs in a competition setting. It is a mixture of sugar and other ingredients that can be rolled or moulded like modelling clay, and dries to a hard, plaster-like substance. It is used to provide major structural pieces for competition showpieces, holding more delicate decorations in place. Professionals guard their personal recipes fiercely, but there are simple recipes available for home enthusiasts.
Dissolve 1/2 tsp cream of tartar in 1/2 cup of warm water in a bowl. Sprinkle the gelatin on top of the water, and allow it five minutes to soften and absorb water.
Sift the five cups of confectioner's sugar repeatedly with the cup of cornstarch, until they are well mixed. Set aside.
Place the bowl on top of a pot of simmering water, and stir until the gelatin is completely dissolved. Pour the gelatin mixture into the bowl of a stand mixer.
Select the mixer's paddle attachment, and start it on the slowest setting. Add the dry ingredients 2 tbsp at a time, until they are completely incorporated. Increase speed to medium, and beat for another three to four minutes, until the paste is light and white.
Shape the pastillage into a flat round, and wrap it tightly in plastic film wrap. Refrigerate for at least 30 minutes before rolling out the dough and using it. Keep unused portions tightly wrapped to prevent drying out.
Pastillage can be tinted easily with small amounts of chocolate or food colouring, to achieve specific pastel shades. Once dried, pastillage is brittle and stiff. It can be sanded or painted, but will break if handled roughly. Pastillage can be made and frozen for later use. Allow it to thaw completely before using. If you don't have access to a stand mixer, use a wooden spoon to mix the pastillage. It will require some arm strength, so if possible arrange for a second pair of hands to help with the mixing. If your pastillage sticks when you roll it, dust your work surfaces with confectioner's sugar in the same way you'd use flour with pie crust.