Low Protein Apple Muffins for the PKU diet. These moist, apple studded low protein muffins are Molly’s all-time favorites and a perfect back to school breakfast on the go or lunch. The brown sugar on the top adds a nice little crunch so don’t skimp out on it. After all, we all know the lid is the best part of a muffin! To access this low protein recipe, please sign up or log in to our free website.