Sift the flour, baking powder, baking soda, salt and custard powder. Keep aside. Mix the mashed bananas and the powdered sugar to combine well.
Now add in the flour, lemon juice, milk and oil and fold in well. Lastly add the raisins and give it a mix.
Place the muffin liners on to the muffin tray and spoon the batter to it. Do not fill it up to the brim, only 3/4 of the muffin liners. (In the absence of the liners, spoon the batter to a greased muffin tray)
Place the tray on the lower rack of a preheated microwave oven in the convection mode and bake at 180 degrees Celsius for 15 minutes.
The top should be brown and do the toothpick test to ensure it is done. Cool on a wire rack for 15 minutes and serve as desired.
