Typically, you use sourdough starter discard when you make quick breads or muffins instead of going through a long fermentation process like your favorite loaves. Since the starter is no longer active, it's not quite powerful enough to give your muffins a nice rise, and you need to add a leavening agent (or two) instead. The same goes with sourdough waffles, sourdough pumpkin bread, and more. I haven't tried fermenting this batter, but if I do, I'll adjust the post with the steps and results.