Preheat oven to 325° F. Spray an 8½ x 4½-inch loaf pan with cooking spray and set aside.
In a large bowl, sift together wheat flour, all-purpose flour, baking soda and salt. Gradually stir in the buttermilk and molasses, mixing just until combined (do not over-mix). Fold in raisins.
Transfer batter to prepared pan, and cover it with buttered (or sprayed) aluminum foil, pressing the foil tight around the edges of the pan (so that the bread will steam a bit), but ballooning it in the center, so that the bread has room to expand without hitting the foil. Bake for 50 minutes. Remove the foil (the middle may be slightly sunken; that's OK), and bake for an additional 10 minutes, or until a toothpick inserted in the center comes out clean.
Notes
Be careful not to over-mix the batter. Add the wet ingredients to the dry ingredients just until they’re combined. Too much mixing and the bread will come out tough or dry. Thekey to keeping a quick bread moist is NOT over-mixing.
Omit the raisins altogether, or use dried cranberries, chopped dates or currants instead.
Add chopped nuts such as walnuts or pecans for a bit of crunch.
Grease the loaf pan really well or spray with a non-stick baking spray so that the bread pops right out.
The buttermilk is an important ingredient in this recipe. The lactic acid in the buttermilk reacts with the baking soda to form tiny bubbles of carbon dioxide, which helps the bread rise. Don’t substitute with a different milk.