How to Make It
Let sorbet stand at room temperature until slightly softened, about 5 minutes. Scoop into a large bowl; break into pieces using a wooden spoon or rubber spatula.
Add lime zest, macadamia nuts, and rum, and gently fold until evenly incorporated.
Spoon sorbet into a 9- x 5-inch loaf pan; cover with plastic wrap, pressing directly onto surface of sorbet. Freeze until firm, at least 2 hours, before serving.