Preheat oven to 200 degrees fahrenheit. Prepare a sheet pan with foil and set aside.
Add salt, peel of lemon, whole sprig of rosemary, and garlic powder to a blender or food processor. Pulse until fully combined.
Spread salt mixture on a sheet pan. Add remaining lemon zest and fresh chopped rosemary and stir to combine. Bake for 20 minutes.
Remove from oven, and allow to cool. Break apart salt clumps with a fork and transfer to airtight container. Lemon salt lasts for up to 3 months when stored in a dark environment.