Preheat oven to 350°.
Lightly spoon all-purpose flour and whole wheat flour into dry measuring cups; level with a knife. Combine flours, baking powder, ginger, baking soda, salt, cardamom, cinnamon, and nutmeg in a large bowl.
Combine milk and next 4 ingredients (through eggs) in a medium bowl, stirring with a whisk until blended. Add sugar, stirring until well blended. Make a well in center of flour mixture. Add milk mixture to flour mixture; stir just until combined. Stir in raisins. Scrape batter into a 9 x 5-inch loaf pan coated with cooking spray, using a rubber spatula. Sprinkle walnuts in a 2 1/2-inch-wide strip down center of loaf.
Bake the loaf at 350° for 1 hour or until a wooden pick inserted in center comes out clean. Cool loaf in pan on a wire rack.
Check your local supermarket for small disposable loaf pans; half-size loaves may be ideal for a bake sale. This recipe also makes 3 (3 1/2 x 5 1/2-inch) loaves; bake them for 50 minutes.
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