The Ideal Lemon Bar: A Fierce Filling and a Strong Supporting Crust

2 cups/240 grams all-purpose flour
1 cup/225 grams very cold unsalted butter (2 sticks), cut into small chunks
½ cup/50 grams sweetened shredded coconut (see note)
¼ cup/30 grams confectioners' sugar, more for sprinkling
Pinch of salt
FOR THE FILLING:
2 cups/400 grams granulated sugar
4 eggs
½ cup/120 milliliters freshly squeezed lemon juice
¼ cup/30 grams all-purpose flour
1 teaspoon baking powder
Pinch of salt

PREPARATION
Make the crust: Heat oven to 350 degrees. Butter a 9-by-13-inch or 9-by-9-inch baking pan, preferably nonstick.
In a stand mixer or food processor, combine crust ingredients. Mix or pulse until well combined and moist clumps form. Using your hands, press evenly but gently into prepared pan.
Bake crust until edges and top are light golden brown, 20 to 25 minutes. Rotate once for even browning.
Meanwhile, make the filling: Whisk all the ingredients together until smooth.
Pour filling over hot parbaked crust and return to the oven. Bake until filling is almost set, about 20 minutes more (thicker squares, baked in the 9-by-9-inch pan, will take longer). Start checking after 15 minutes; when you give the pan a gentle shake, filling should be lightly set all over and still quivery in the very center.
When baked, let cool completely in the pan on a wire rack. Sprinkle the top lightly and evenly with confectioners' sugar.
Cut into squares, diamonds or rectangles and remove from pan. Keep refrigerated until ready to serve. If desired, sprinkle again with confectioners' sugar just before serving.

https://cooking.nytimes.com/recipes/1018804-best-lemon-bars