Banana-rhubarb Muffins

• 2 egg whites
• 250 gr oat flour blend
• 160 ml skim milk
• 100 gr sugar
• 90 gr rhubarb (chopped fresh)
• 75 gr mashed ripe banana
• 60 ml vegetable oil
• 14 gr baking powder
• 1 gr salt
• 1 gr nutmeg