Preheat oven to 350°.
Combine raspberry jam and walnuts in a small bowl.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, baking soda, and salt in a bowl, stirring with a whisk. Combine sugar, butter, lemon rind, 1 teaspoon vanilla, egg, and egg white in a large bowl; beat with a mixer at medium speed until well blended. Add flour mixture and sour cream alternately to sugar mixture, beginning and ending with flour mixture.
Spread half the batter into an 8 x 4-inch loaf pan coated with cooking spray. Spoon raspberry mixture over top, leaving a 1/4-inch border. Spread remaining batter over raspberry mixture.
Bake at 350° for 55 minutes or until wooden pick inserted in center comes out clean. Cool in pan 10 minutes on a wire rack; remove from pan. Cool completely on wire rack. Combine 1/8 teaspoon vanilla , powdered sugar, and milk in a small bowl, stirring well with a whisk. Drizzle over loaf.