Muffin Batter:
1 cup unbleached flour
3/4 cup yellow cornmeal, preferably stone-ground
1/2 cup whole wheat flour
2 teaspoons baking powder
1/2 teaspoon salt
1/4 teaspoon cinnamon
1/4 teaspoon nutmeg
1/4 teaspoon ground ginger
1 large egg
1 cup milk
1/3 cup flavorless vegetable oil
1/4 cup unsulphured molasses
Crumb Topping:
2 tablespoons yellow cornmeal, preferably stone-ground
1 1/2 tablespoons unbleached flour
2 tablespoons packed light brown sugar
Pinch of salt
1 tablespoon cold unsalted butter
Preheat the oven to 400 degrees F. and butter 12 muffin cups. To make the muffin batter, stir the unbleached flour, cornmeal, whole wheat flour, baking powder, salt, and spices together in a large mixing bowl. In a separate bowl, beat the egg lightly, then whisk in the milk, oil, and molasses. Set aside.
Make the crumb topping by combining the crumb ingredients in a mixing bowl and then rubbing them between your fingers until you have large, damp crumbs.
Make a well in the dry ingredients, add the liquids, and stir with a few deft strokes, just to blend. Divide the batter evenly among the muffin cups. Sprinkle some of the crumb topping on each muffin and bake for 18 to 20 minutes. When the muffins are done, the topping should be browned lightly and the muffins themselves slightly springy to the touch. Cool the muffins on a rack in the pan for 5 minutes, after which they should lift right out. Serve them hot, storing leftovers in a sealed plastic bag for up to 2 days. To reheat, wrap in foil and place in a hot oven for 5 minutes.