Preheat oven to 190 degrees C. Grease a 12-cup standard muffin tin or line cups with paper cases.
Combine crushed bran flakes, wholemeal flour, sucralose, ground flaxseed, plain flour, baking powder, ground cinnamon, bi carb soda and salt in a bowl. Make a well in the middle of the mixture.
Whisk egg whites together lightly in a bowl until foamy. Mix in buttermilk, honey and applesauce. Pour mixture into the well and blend batter until just moistened. Fold in cranberries.
Fill muffin cups 3/4 full with batter; sprinkle tops with whole flaxseeds.
Bake in the preheated oven until tops spring back when lightly pressed, 12 to 15 minutes. Cool in the pan for 5 minutes; transfer to a wire rack to cool completely, about 15 minutes.