Like so many baked goods, what makes a perfect muffin is likely to depend on the eater’s personal preferences. I identify a good muffin by its crispy top, moist interior, and plenty of inclusions. (I once attempted to exchange a muffin at a bakery because I could only spot a single, lone blueberry.) There are a few rules to keep in mind—most importantly, not overmixing the batter. The more you mix, the more the batter will develop gluten—those dangerous protein strands which are desirable for bread baking but can make a muffin unnecessarily tough. Mix just until the ingredients are thoroughly combined and homogenous, then move on.