Preheat oven to 350°F (177°C) (see Chef’s Tips).
Lightly grease and line a 9 x 13-inch baking pan with parchment paper, leaving a 2-inch overhang on the longer sides.
In the bowl of a food processor fitted with a metal blade, add in the Redpath® Golden Yellow Sugar and lemon zest. Process until fragrant and thoroughly combined. Add in the flour, cornstarch, and salt. Pulse until well mixed, and no lumps remain. Add in the cubed butter and pulse until it just begins to clump together into a ball.
Evenly press the dough into the prepared pan. Use a flat-bottomed drinking glass or dry measuring cup to smooth out any lumpy areas. Place into the fridge to chill; 10 minutes.
Dock the surface of the chilled dough with a fork. Place into the preheated oven and bake until golden; about 20 to 25 minutes.
While this bakes, make the filling (see Chef’s Tips).