Preheat oven to 400 degrees F. Coat 12 large (1/2-cup) muffin cups with cooking spray or line with paper liners.

Use a vegetable peeler to remove the zest from the lemon in long strips. Combine the zest and sugar in a food processor; pulse until the zest is very finely chopped into the sugar. Add buttermilk, oil, egg and vanilla and pulse until blended.

Combine whole-wheat flour, all-purpose flour, baking powder, baking soda and salt in a large bowl. Add the buttermilk mixture and fold until almost blended. Gently fold in raspberries. Divide the batter among the muffin cups.

Bake the muffins until the edges and tops are golden, 20 to 25 minutes. Let cool in the pan for 5 minutes before turning out onto a wire rack. Serve warm.

Tip: No buttermilk? Mix 1 tablespoon lemon juice into 1 cup milk.

Shopping Tip: White whole-wheat flour, made from a special variety of white wheat, is light in color and flavor but has the same nutritional properties as regular whole wheat. Whole-wheat pastry flour can be used as a substitute here. Both can be found in the natural-foods section of the supermarket or online from King Arthur Flour, bakerscatalogue.com.

MAKE AHEAD TIP: Wrap each in plastic and freeze in a freezer bag for up to 1 month. To reheat, remove plastic, wrap muffin in a paper towel and microwave on High for 30 to 60 seconds.