While culinary writers have long emphasized the decorative and aesthetic application of icing -- the sugar-rich coating embellishing cakes, buns, and pastry, also known as frosting -- few have addressed its impact on the sense of taste. Like a puff of steamed milk on the brim of a cappuccino or the deep richness of a glazed doughnut, icing, through its decadent warmth, overwhelms the taste receptors. In doing so, the dessert is marked both by sight and by taste as an object of celebration. The following discussion focuses on the various forms of icing, its culinary and visual manifestations.

The most simple icing is a syrup or glaze of sugar and water, or sugar and milk. The mixture is boiled and then brushed over the tops of yeast-raised foods while warm. Once dry, the result exudes a pearly radiance.

A simple icing of water and powdered sugar adorns common English desserts such as Victoria sandwich cakes (a plain cake made by the creaming method, closely related to pound cake) and danishes.

More complex is the glacé form in which icing sugar is added to boiling sugar syrup and beaten. To this glossy mixture is added floral (violet, jasmine, rose), fruited (orange, lemon, raspberry), or autumnal (chocolate, coffee, cinammon) essences. Cakes topped with these icings are often halved and lined with buttercream (one part butter to two parts icing sugar creamed together to a fluffy consistency).

These relatively simple icing cakes are ceremoniously ornamented with glacé cherries, angelica (more about these in candied fruit), silver dragées (French sweetmeat composed of a nut - usually an almond - or fruit coated with layers of hard sugar, lined with liqueur), hundreds and thousands (tiny dragées made by coating individual sugar crystals with sugar syrup; the result is brightly scented and colored in red, orange, pink and yellow), and other colorful delights.

A fondant icing -- fondant being a milky-sweet coating applied to fresh fruit, espresso beans (since the late-1940's), mint, or chopped nuts -- adds warm syrup, flavor, and fragrance to ordinary fondant. The resultant icing exudes a soft, satiny sheen for use on show cakes.

Royal icing aspires for a stiff, opaque brilliance for use on expensive British Christmas and wedding cakes. It is prepared by beating icing sugar with egg whites, lemon juice or orange flower water (produced by the distillation of orange flowers; Middle Eastern in origin), and an almost imperceptible amount of powdered sugar. The master confectioner can exhibit his or her virtuosity by applying royal icing in the following ways:

  1. By producing a perfectly flat, smooth surface on to which decorative etchings may be applied;
  2. By embedding layer upon layer of intricate borders, patterns, and trellis work which convey fragility even while being very firm when set;
  3. By making runouts, flat shapes of icing which are allowed to dry and then mounted onto the cake as collars, plaques, or free-standing ornaments.

A royal icing is most often applied atop a thin layer of marzipan (paste of crushed almonds, egg, and sugar, with a rich, luxurious texture) or a hazelnut spread. While the pleasure of eating a cake with a double spread is immense, the application has a practical purpose as well: the smooth surface of the marzipan acts a seal, protecting a properly finished cake for months.

Source: Healy, Bruce. The Art of the Cake. New York: William Morrow, 1999.