Blueberry-Coriander Buttercream Frosting
A simple Swiss meringue lightens this buttercream frosting, making it easy to incorporate add-ins such as a homemade Blueberry-Corriander Jam. “It has such a great pillowy consistency, but it's very stable" says Sasha Piligian, who shared her technique. "I can manipulate it in endless ways, folding in curd, tahini, jam—the possibilities are endless.” Use high-butterfat (82% to 84%) butter, such as Kerrygold or Plugrá, for the richest taste. For a shortcut, use store-bought blueberry or blackberry jam.
Frosting can be made up to 1 day ahead and refrigerated in an airtight container. Let come to room temperature, about 1 hour. Re-whip until fluffy.