Why It Works
- Using toasted sugar brings the overall sweetness into balance, adding complexity of flavor.
- Liquid ingredients help the sugar dissolve and can add a note of flavor.
- At 155°F (68°C), the egg yolks will be fully cooked.
- Testing the finished buttercream with a thermometer helps rule out problems related to temperature, a common concern in recipes built on butter.
The rich custard flavor of French buttercream gives this pistachio frosting a gelato-like quality that’s hard to resist, with a hint of caramel from toasted sugar, and splash of liqueur to add a complementary note (we love how the herbs in Cardamaro underscore the grassiness of pistachio, while Maraschino can play up its fruity/nutty side, but even rum works in a pinch).
Homemade pistachio paste gives this frosting the best color, consistency, and flavor, particularly when made with Sicilian pistachios. Take care when working with commercial pastes, as they can vary considerably from brand to brand, due to various proportions of added sugar and oil.
