Sift together the flours, baking powder, baking soda and cinnamon powder and keep aside.
Mix brown sugar into the curd till completely dissolved. Add the oil and vanilla essence and mix well.
Add the wet mixture to the dry flour mixture and stir till just mixed. Don't stir too much or you'll end up with tough muffins!
Add the grated apple and mix through with a fork.
Preheat the oven to 180 degrees Celsius. Grease and flour the muffin cups. Divide the batter evenly among the cups, till two-thirds full.
Bake for 25 minutes or till done. To check if it's ready, insert a toothpick into the center of a muffin. If it comes out clean, the muffin is completely cooked. Let cool before serving.