Grease 7 x 11 in. baking pan. Preheat oven to 350 f. Resisft flour with baking powder and salt. Cream butter and sugar; beat in egg. Stir in 1/4 cup Kahlua, then add flour mixture, stir until well blended. Fold on chocolate pieces and nuts. Spread evenly in prepared pan. Bake 30 mins. or until top springs back when touched lightly in center. Do not over bake. Remove from oven and cool 15 mins. then brush top with 1 tblsp. Kahlua. Frost when completely cooled. BROWN BUTTER ICING: In a saucepan heat butter until lightly browned. Remove from heat. Add Kahlua, milk or cream and sifted powdered