If using frozen blueberries, don’t thaw, use them frozen. If your blueberries (or any frozen, brightly colored, juicy berry) are even just a little bit thawed; take two tablespoons of the dry ingredients and dredge your berries to cover before adding to your batter. This will avoid the juice running into your batter and turning the entire batch purple. Some people like a purple muffin, and hey if that’s you, please proceed. To me, that just says “I don’t know how to keep the berries from staining my batter” but, I promise not to judge. (Unless you’re a professional in which case I shall “tut-tut” under my breath.) However, your blueberry bits will be a little drier. Bake on my friend, bake on!