In a large mixing bowl, add sugar and zest - use your fingers to massage the zest into the sugar until very fragrant and combine.
Add butter and beat mixture together until smooth.
Add juice and mix until combined and creamy, making sure to scrape down the sides as needed. Add flour and salt beat just until the mixture resembles coarse crumbs.
Scoop mixture into a 9" x 13" baking pan coated with nonstick spray.
Place into the oven and bake until the top is lightly golden, about 25 to 35 minutes.
Remove and place pan on a wire rack to cool completely
To prepare the glaze
In a small bowl, whisk together confectioners' sugar, butter and lemon juice until smooth.
Spread glaze over the cooled shortbread and sprinkle with lemon zest, if desired.
Set aside and let stand at least 30 minutes before cutting.
Makes about 40 cookies.
Notes
Rub the lemon zest into the sugar. Don’t skip this step! Rubbing the zest into the sugar releases the oils from the lemon peel and gives the cookies their bright, fresh lemon flavor.
Use fresh lemons. Fresh lemon zest and juice make a huge difference in flavor compared to bottled juice.
Don’t overmix the dough. Mix just until the dough comes together to keep the shortbread tender and buttery.
Chill the dough if needed. If the dough feels soft or sticky, chill it for 20–30 minutes before rolling or shaping for easier handling.
Watch the bake time carefully. Shortbread should stay fairly light in color. You want lightly golden edges, not deeply browned cookies.
Let the cookies cool before glazing. If the cookies are still warm, the glaze will melt right off instead of setting up nicely.
Adjust the glaze consistency. Add more powdered sugar for a thicker glaze or a little extra lemon juice for a thinner drizzle.
Make them ahead. The dough can be made several days in advance and stored in the refrigerator until ready to bake.
Store for freshness. Keep baked cookies in an airtight container in the refrigerator for up to several weeks or freeze them for longer storage.
Perfect for gifting. These cookies hold up beautifully and ship well, making them a great choice for holiday cookie boxes or neighbor gifts.