- 2 cups walnut halves and pieces
- 1 cup sugar
- 1/2 tsp plus 1 pinch of salt
- 1/2 cup butter, unsalted, at room temperature
- 4 eggs, separated
- 1 cup powdered sugar
Preheat oven to 350 F. Butter an 8-inch square baking pan and line the bottom with wax paper or parchment.
In a food processor, finely grind 1 cup of the walnuts with 1/4 cup sugar and 1/2 teaspoon salt.
In a medium bowl, using an electric mixer, beat 4 tablespoons of butter with the remaining 3/4 cup sugar until pale and fluffy. Beat in the egg yolks, one at a time, making sure each is incorporated before adding the next. Stir in the ground walnut mixture.
In a separate mixing bowl, beat the egg whites with a pinch of salt until stiff peaks form. Gently fold the beaten whites into the walnut batter and pour batter into the prepared pan. Tilt the pan to evenly distribute the batter.
Bake for about 40 minutes or until the cake is set and begins to pull away from the side of the pan. Transfer to a rack and let cool completely.
In a food processor, pulse the remaining 1 cup of walnuts with the powdered sugar until finely ground. Add the remaining 4 tablespoons of butter and pulse until creamy. Spread the frosting evenly over the bars. Using the edge of a tablespoon, make a decorative pattern in the frosting. Dust with any remaining finely chopped walnuts.
Cut into 1x2-inch bars. Makes 32 bars.