Heat oven to 325 degrees F. Line bottom and sides of 13 x 9 x 2-inch baking pan with nonstick or regular foil.
In medium-size microwave-safe bowl, combine butter and white chocolate. Microwave on 100 per cent power 1 minute; stir until melted. (Or melt together butter and chocolate in top of double boiler.) Let cool slightly.
In large bowl, beat eggs and salt until light and fluffy, about 3 minutes. Add sugar and vanilla; beat until thick and creamy, 2 minutes more.
Beat in slightly cooled chocolate mixture. On low speed, beat in flour. Fold in nuts. Spread evenly into prepared pan.
Bake in 325 degree F oven 35 to 45 minutes or until top is golden and center is just set. Let cool completely in pan on wire rack. Makes 20 brownies.