Preheat oven to 400o F. Coat 12 large (1/2-cup) muffin cups with cooking spray, or line with paper liners.
Combine lemon zest and sugar in a food processor; pulse until blended.
Add yoghurt, oil, egg, and vanilla. Pulse until blended.
Combine whole-wheat flour, baking powder, baking soda, and salt in a large bowl. Add the yoghurt mixture, and fold until almost blended. Gently fold in raspberries. Divide the batter (it will be thick) among the muffin cups.
Bake the muffins until the edges and tops are golden, 18 to 25 minutes. Let cool in the pan for five minutes before turning out onto a wire rack. Serve warm.