Make the Coconut Crust:

1. Preheat and prep: Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving overhang on two sides for easy removal later. This makes cutting and serving so much easier.
2. Mix the crust: In a medium bowl, combine flour, coconut, powdered sugar, and salt. Stir with a fork to distribute everything evenly. Pour the melted butter (and coconut extract if using) over the dry ingredients. Stir with a fork or spatula until the mixture is evenly moistened and resembles wet sand. All the dry ingredients should be coated with butter—there shouldn’t be any dry pockets.
3. Press the crust: Transfer the crust mixture to the prepared pan. Using your hands or the bottom of a measuring cup, press the mixture firmly and evenly into the bottom of the pan. Make sure to press into the corners and create an even layer across the entire surface. A firmly pressed crust prevents it from crumbling later.
4. Pre-bake the crust: Bake the crust for 18-20 minutes until it’s lightly golden brown around the edges and set in the center. It should look dry and no longer greasy. Remove from the oven and set aside while you prepare the filling. Leave the oven on.

Make the Lemon Filling:

5. Whisk the filling: While the crust is baking, prepare the lemon filling. In a large bowl, whisk together the eggs and granulated sugar vigorously for about 1 minute until the mixture is smooth and slightly lighter in color. Add the lemon juice and lemon zest, whisking until well combined.
6. Add flour mixture: In a small bowl, whisk together the flour and baking powder. Sprinkle this over the egg mixture and whisk gently until just combined and smooth. Don’t overmix—you just want to incorporate the flour without creating lumps.
7. Pour over crust: Once the crust has finished its initial bake, pour the lemon filling evenly over the warm crust. The crust should still be hot or warm when you add the filling. Use a spatula to spread the filling into an even layer if needed, making sure it reaches all corners.

Bake and Cool:

8. Bake the bars: Return the pan to the oven and bake for 20-25 minutes. The filling is done when it’s set around the edges but still has a slight jiggle in the very center when you gently shake the pan. It should look puffy and the surface should be matte, not shiny. Don’t overbake or the filling will be grainy instead of creamy. The filling will continue to set as it cools.
9. Cool completely: Remove from the oven and place the pan on a wire cooling rack. Let cool to room temperature, which takes about 1 hour. Once cooled, cover the pan with plastic wrap or foil and refrigerate for at least 2 hours or preferably overnight. Chilling is essential for clean cuts and the best texture.

Toast Coconut and Finish:

10. Toast the coconut: While the bars are chilling, toast the remaining coconut. Spread it in a dry skillet over medium heat, stirring frequently, for 3-5 minutes until golden brown and fragrant. Watch carefully as it can burn quickly. Let cool completely.
11. Cut and serve: When ready to serve, use the parchment overhang to lift the entire slab out of the pan onto a cutting board. Sprinkle with toasted coconut and dust with powdered sugar if desired. Using a sharp knife (wipe clean between cuts), cut into 24 bars (6 rows by 4 rows). For the cleanest cuts, the bars should be completely chilled.