Preheat oven to 350º F. Spray 8 x 2 in. or 9 x 2 in. square pan with vegetable pan spray.
In small bowl, combine flour, baking powder and salt. In small saucepan, melt butter and brown sugar; stir until sugar is dissolved. Remove from heat and let cool about 5 minutes. Stir in eggs and vanilla; mix well. Add flour mixture; mix until blended. Fold in pecans. Spread batter into prepared pan.
Bake 30-35 minutes or until toothpick inserted in center comes out clean. Cool completely before cutting.
Makes about 16 square brownies.