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Three things make Costco muffins special: they’re huge, they’re moist, and berries are bursting out of the top of each one. Now your home muffins can be just as special using a similar recipe and freshly unlocked tricks from our favorite big box store.
Obviously, you get huge muffins by using a huge muffin pan, so you’ll need a jumbo or “Texas-size” muffin pan if you want your muffins the same size as the originals. You can certainly make standard muffins with this batter in a standard size muffin pan, but in this case, bigger is definitely better.
To get muffins that are moist you’ll need oil. I noticed many muffin recipes use butter, but I found it made the muffins taste more like butter cake or pound cake than true muffins. Looking at the ingredients listed on the package of Kirkland muffins, you won’t find any butter in there. Just oil. For this hack, some of that oil comes from margarine (for a mild butter flavor and thicker batter), and the rest is vegetable oil.
As for the blueberries, if you add them straight into the batter the juice frozen on the outside of the berries will streak your batter blue, so be sure to rinse the berries before you add them. And to make your muffins look as irresistible as those at Costco, we’ll use another one of their tasty tricks: press 4 blueberries into each cup of batter just before the pan goes into the oven so that every baked muffin is sure to have several tantalizing berries popping out of the top.