From America's Test Kitchen Season 2: Muffins and Scones
A good blueberry muffin should be rich, moist, and delicate—but still packed with fresh berry flavor. We wanted our muffins to be smaller and more delicate than the big, bland store-bought versions.
Instead of simply stirring, we whisked together the wet ingredients—starting with egg and sugar, then adding the butter and sour cream. It’s important to use light strokes when mixing the wet and dry ingredients, as these muffins become tough when overmixed. Another discovery was that wild, frozen blueberries are not just more convenient and less expensive than out-of-season fresh berries, they distribute nicely in the muffins. Because frozen berries tend to bleed and become gummy, they should remain completely frozen until stirred into the batter.
Makes 12 muffins
This recipe does not require a standing mixer, but when making the batter, be sure to whisk vigorously in step 2, then fold carefully in step 3. There should be no large pockets of flour in the finished batter, but small occasional sprays may remain. Do not overmix the batter. These muffins are great unadorned, but for an extra flourish, give them a dip in sugar by following one of the variations.