Preheat oven to 350 degrees.
In a medium bowl, whisk together flour and salt.
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 mixture and 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