Preheat oven to 170° Line a 12 hole muffin tray with paper cases.
Sift flours and baking powder together into a large bowl (tip in remaining wholemeal flakes after sieving). Add brown sugar and white chocolate and stir to combine, making sure there are no lumps in brown sugar.
Mix baking soda and warm milk until soda has dissolved. Mix with remaining wet ingredients in a separate bowl and mix until well combined.
Make a well in the dry ingredients and pour in the wet mixture. Stir gently until just combined –but don’t overmix, lots of lumps will ensure a lighter muffin! Spoon mixture into paper cases, dividing equally.
Bake for 20-25 minutes, until golden brown and the muffins bounce back when lightly pressed. Remove from oven and transfer to a wire rack to cool slightly. Scrumptious eaten warm, fresh from the oven. If eating at a later time, you can always gently warm them in the microwave for about 15 seconds before eating.