Preheat oven to 375 °F (190 °C). Butter a 12-cup nonstick muffin pan or line with paper liners. In a bowl, combine cranberries, milk and yogurt. In a large bowl, combine all-purpose and whole wheat flours, flax seeds, baking powder, cinnamon, baking soda and salt. Whisk sugar, egg, and butter into Milk mixture; pour over dry ingredients and stir just until moistened.
Spoon into prepared muffin pan. Press a few extra cranberries gently into tops if desired. Bake for 20 to 25 min or until tops are firm to the touch. Let cool in pan for 10 min. Transfer to rack to cool completely.