Three things make Costco Blueberry 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 like Kirkland's, 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 my Costco Blueberry Muffin copycat recipe, 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 the batter in each cup 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.

Find more favorite famous bread recipes here. 

The real Costco muffins taste great, but they may not be as wholesome as you’d like. The dough has been conditioned with gums to thicken it and ingredients to emulsify it, and to preserve their shelf-life, the muffins contain no butter. The flavors you taste—butter, almond, and vanilla—are artificial.

I attempted to stay true to the original ingredients in my first take on the famous muffins with this copycat recipe for Costco’s Blueberry Muffins. In that hack, I chose to avoid butter like the real muffins do, opting instead for margarine. And since the Costco muffins contain no buttermilk, I also stayed away from that ingredient, even though I love its magical properties in baking.

This time though, I’m taking a different approach by using more whole egg, real butter, and, yes, buttermilk to bring great flavor and a better crumb to our finished product. Without all the dough conditioners found in the original, these cloned muffins have a pleasant homemade charm, and the flavor is more appealing because it’s real.

Find more favorite famous bread recipes here. 

The huge muffins sold at Costco’s bakeries had been one of my longtime favorite picks from the big box store, partly because they were so deliciously big. But in late 2024, the chain altered its portion size to the chagrin of many muffin fans, and now the store’s famous jumbo muffins are not so jumbo. Today, Costco’s muffins are roughly half their former size. The muffins still taste great, but if you prefer the original massive muffins in all their supersized splendor, you’ll need to take matters into your own hands.

My previous hacks for Costco Blueberry Muffins and Costco Almond Poppyseed Muffins each produce giant muffins, so I designed this recipe the same way. To make my Costco Lemon Raspberry Muffins copycat recipe, you’ll need a jumbo, or Texas-size, muffin pan that will re-create the bigness of the store’s original version. If you don’t have one of those pans, you can still make regular-sized muffins using this recipe and a standard 12-cup muffin pan.

Find more favorite famous bread recipes here.