Set aside one tablespoon of oat flakes in advance. Chop the rest in a blender. Break two eggs and separate the whites from the yolks. Mix the yolks with sugar. Add yogurt, crushed flakes, baking powder and lemon juice. Stir until smooth.
Add raisins and a spoonful of whole flakes to the resulting mixture. Mix it up.
Beat the whites with a pinch of salt until creamy. Add to the finished dough and mix.
Lubricate the muffin pan with oil and form future cupcakes from the finished mixture. Put in a preheated 180 degree oven for 30 minutes.