Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a large bowl, cream together the softened butter and sugar until light and fluffy. Add the lemon zest and mix well.
Gradually add the sifted flour and salt, mixing until the dough just comes together.
Roll the dough into 1-inch balls and place them onto the prepared baking sheets. Flatten each ball slightly with the bottom of a glass. Sprinkle with additional sugar if desired.
Bake for 18-20 minutes or until the edges are a light golden brown. Allow to cool on a wire rack.
Notes
Ensure the butter is at room temperature for a smooth dough. Store cookies in an airtight container for up to one week.