When I'm writing a restaurant dessert menu, I feel a bit like Goldilocks in my quest to create a selection of sweets that's "just right." I try to balance the offerings so that all diners will find something that appeals to them. Chocoholics crave rich and dark chocolate desserts; other customers like to end their meal with something light and fruity; vanilla—no surprise here—is always a huge hit. But of all the flavors I have to work with, the one that I love the most is coffee. Why? Coffee is rich without being overwhelming. Its bitter edge elevates a dessert from one-dimensional sweetness to refined sophistication. And coffee as a flavoring couldn't be easier to use. Adding it to custards, ice creams, cakes, and fillings usually consists of little more than grinding some beans and can even be as easy as opening a jar of instant coffee.
Different forms—bean, powder, and liquid—give you flavoring options. I love eating coffee desserts because I am addicted to the bittersweet flavor; I love making coffee desserts because coffee is a snap to use. Its intense flavor can be added to a dessert in a variety of ways.
Whole beans pack the most flavor. For the most intense coffee flavor, I turn to whole beans, preferably espresso roast. Using whole beans that I crush or grind myself appeals to the purist in me. But more important, whole beans have more flavor than preground, since coffee loses its flavor and aroma exponentially after being ground. To extract even more flavor from the beans, I roast them in the oven for a few minutes to encourage their flavorful oils to emerge.
Give the sponge cake for tiramisú a good soaking for the best texture. Here, a generous amount of black coffee is brushed onto the cake to make it very moist.
If I'm infusing a custard or an ice-cream base with coffee flavor, I crush the beans coarsely, with a rolling pin (put the beans in a zip-top bag first to keep them from flying all over the kitchen) or a food processor, and steep them in the liquid (the pieces get strained out later). If they're going into cookie or cake batter, I grind the beans finer.
Instant coffee and instant espresso add flavor quickly. I recommend that people always keep a jar of instant espresso powder or instant coffee in the fridge. I like these freeze-dried forms because they add flavor immediately, without needing to steep as beans do. For instance, you can mix a little powder into ganache or pastry cream while it's warm to quickly give coffee flavor to the dessert. And instant offers the convenience of "brewing" just a cup at a time. It also allows for a more standard result, since people brew coffee so differently, ranging from really weak to really strong.
Coffee liqueurs add sweet coffee flavor with a zing. When I want to jazz up a dessert, I turn to coffee liqueurs like Kahlúa and Tia Maria. For example, I'll mix some into vanilla creme anglaise for a coffee-spiked custard sauce. Because the alcohol-based flavors diminish when cooked, I generally add liqueurs to desserts after they're cooked. An exception is the filling for the Tiramisú recipe; because the sabayon is cooked only briefly over low heat, I add the liqueur with the other ingredients.
Brewed coffee works best to bolster other forms of coffee. I find that using brewed coffee as the only coffee flavoring in a recipe doesn't pack enough coffee flavor, so I almost always use it in conjunction with another form of coffee, a sort of coffee reinforcement (for how to do this, see "Brewing coffee for use in baking," below).