Making your own bitters is a labor of love, so use the highest-quality ingredients you can, such as unwaxed organic citrus and top-shelf vodka. Gentian can be found online or at some health-food stores.
A Swiss meringue may sound fancy, but it's really very simple to make. For browning the meringue, you'll need a small kitchen blowtorch (available at amazon.com). The cookies can be made up to two days ahead and stored at room temperature, and the curd can be made up to a week ahead and stored in the refrigerator. The assembled cookies can be made ahead and stored at room temperature one hour or in the refrigerator (do not cover) up to six hours. Remove from the refrigerator 30 minutes before serving.
Cacio e pepe is practically synonymous with Pecorino Romano -- but Pecorino clumps when cooked. Add it at the end, instead, which also makes the most of its sharp flavor. Lemon adds spunk -- that is, acidity and freshness.
The delicate flavor of Meyer lemons can get lost in the shuffle of most lemon desserts. But this recipe is the perfect reason to seek out the special citrus; the simple curd filling really lets them shine. The dish was inspired by recipes in "Chez Panisse Desserts," by Lindsey Remolif Shere.