Line 9x5-inch loaf pan with foil, with ends of foil extending over sides; spray with cooking spray. Combine flour, baking powder and salt. Beat butter and 1 cup sugar in large bowl with mixer until light and fluffy. Blend in lemon zest, then eggs, 1 at a time. Add flour mixture alternately with sour cream, beating well after each addition. Stir in nuts. Pour into prepared pan.