White Chocolate Macadamia Nut Blondies

3/4 cup (1 1/2 sticks) unsalted butter

2 cups all-purpose flour

2 cups firmly packed light brown sugar 

1 teaspoon baking powder

1 teaspoon salt

3 large eggs, lightly beaten

1 tablespoon vanilla extract

1 cup chopped macadamia nuts

1 1/2 cups white chocolate chips, divided

Coarse salt, for garnish 

Heat oven to 350 F. Line a 9 x 13-inch baking pan with parchment. 

In a small saucepan over medium heat, melt butter. Continue cooking, swirling pan from time to time, until butter smells nutty and small light-brown flecks have settled to the bottom of the pan, 6 to 8 minutes. Pour butter into a small bowl and let cool. 

In a large bowl, stir together the flour, brown sugar, baking powder and salt. Add butter, eggs and vanilla; stir until just combined. Stir in white chocolate chips and nuts. 

Pour batter into the prepared pan; spread into an even layer. Sprinkle evenly with remaining chips. Bake until a toothpick inserted in the center comes out clean, 22 to 27 minutes. Sprinkle lightly with coarse salt. Let stand 30 minutes before removing from the pan and cutting into bars.