Ingredients
1 cup (2 sticks) unsalted butter, room temperature
3 cups packed light-brown sugar
2 1/4 cups all-purpose flour
2 cups sweetened shredded coconut
2 teaspoons baking powder
4 large eggs, lightly beaten
2 teaspoons pure vanilla extract
2 cups finely chopped toasted walnuts
Preparation
Preheat oven to 350 degrees. In a medium bowl, beat together butter, 1 cup brown sugar, and 2 cups flour until mixture comes together to form a dough. Press evenly into a rimmed 11-by-17- inch baking sheet. Bake until just golden, about 15 minutes. Remove from oven; let cool slightly.
Meanwhile, pulse coconut in a food processor several times, until coarsely chopped, then transfer a large bowl. Stir in remaining 2 cups brown sugar and 1/4 cup flour along with baking powder, eggs, vanilla, and nuts. Spread mixture evenly over cooled crust.
Bake, rotating sheet halfway through, until crust is golden brown and filling is set, about 20 minutes. Remove from oven; transfer to a wire rack to cool completely. Cut into triangles with a serrated knife. Store up to 2 days in an airtight container at room temperature.
