1. Preheat oven to 325°. Beat butter at medium speed with a heavy-duty electric stand mixer until creamy. Gradually add sugar, beating until light and fluffy. Add eggs, 1 at a time, beating just until blended after each addition.
2. Stir together flour, salt, and baking soda. Add to butter mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in zucchini and next 2 ingredients. Spoon batter into 3 greased and floured 5- x 3-inch disposable aluminum foil loaf pans (about 1 1/3 cups batter per pan).
3. Bake at 325° for 40 to 45 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes; remove from pans to wire racks, and cool completely (about 30 minutes).