01 - Preheat the oven to 350°F. Line a 9x9-inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
02 - In a mixing bowl, cream together the butter and sugar until light and fluffy. Add the flour and salt, mixing just until combined.
03 - Press the dough evenly into the bottom of the prepared pan. Bake for 15–18 minutes, until just set and lightly golden at the edges. Remove from oven but leave the oven on.
04 - While the base bakes, whisk together the sugar, eggs, lemon zest, lemon juice, and smoked vanilla extract in a medium bowl until smooth. Sift in the flour and whisk until combined. Fold in the shredded coconut.
05 - Pour the lemon coconut mixture evenly over the warm shortbread base. Sprinkle 1/2 cup shredded coconut over the top.
06 - Bake for 18–20 minutes, until the filling is set and lightly golden.
07 - Cool completely in the pan on a wire rack. For easier cutting, chill in the refrigerator for at least 1 hour.
08 - Lift out of the pan using the parchment paper, cut into bars, and dust with powdered sugar if desired.