Costco Blueberry Muffin Copycat Recipe
Those giant Costco blueberry muffins have a loyal following for a reason: they’re dense, bakery-tall, and packed with real blueberries in every bite.
This copycat recipe gets you the same oversized, crisp-topped muffin at home, and it comes together in about 40 minutes.
Why I Love This Recipe
The tops bake up with that crackly sugar crust that Costco’s version is known for, and the crumb stays moist for a couple of days because of the sour cream in the batter.
These are genuinely big muffins, the kind that feel like a proper breakfast rather than a snack. One is enough.
You only need one bowl and about 10 minutes of hands-on work.
Recipe Ingredients
- 2 cups all-purpose flour – Spooned and leveled, not scooped straight from the bag, or the muffins bake up dense
- 1 tbsp baking powder – Fresh baking powder gives you the tall dome; old powder falls flat
- ½ tsp salt – Balances the sweetness
- 1 cup granulated sugar – For the batter
- 2 tbsp granulated sugar – Reserved separately for the crust topping
- 2 large eggs – Room temperature; they incorporate more evenly than cold eggs
- ½ cup sour cream – Full-fat; this is what keeps the crumb tender and moist
- ½ cup whole milk – Whole milk gives a slightly richer crumb than low-fat
- ½ cup unsalted butter – Melted and cooled slightly; salted butter works if you skip the added salt
- 1 tsp vanilla extract – Plain extract, not imitation
- 2 cups fresh blueberries – Or frozen, unthawed; see the note in Variations
Variations / Substitutions
- Frozen blueberries – Use them straight from the freezer without thawing; thawed berries bleed purple into the batter and the texture suffers.
- Greek yogurt for sour cream – Full-fat plain Greek yogurt swaps in 1:1 and gives a very similar result, slightly tangier.
- Lemon zest – Add 1 tsp of zest from 1 lemon to the wet ingredients for a bright, citrusy edge that works well against the blueberries.
- Dairy-free – Use a plant-based butter, oat milk, and a dairy-free yogurt in the same quantities; the muffins bake slightly flatter but still taste good.
- Turbinado sugar topping – Swap the 2 tbsp granulated sugar for turbinado (raw) sugar for a coarser, crunchier crust that gets even closer to the Costco original.
- Lemon blueberry variation – If you enjoy the lemon addition, you might also want to look up Starbucks Blueberry Scones Copycat Recipe for another take on that flavor combination.
How To Make Costco Blueberry Muffins
Step 1: Combine the Dry Ingredients
Preheat your oven to 425°F (220°C), then line a standard 12-cup muffin tin with paper liners or grease it well. In a large bowl, whisk together the 2 cups all-purpose flour, 1 tbsp baking powder, ½ tsp salt, and 1 cup granulated sugar until everything is evenly distributed, about 30 seconds.
The flour mixture should look uniform with no visible clumps of baking powder. This single-bowl approach means you mix the wet ingredients right into the same bowl, so make a well in the center now and save yourself an extra dish.
Step 2: Whisk the Wet Ingredients Into the Batter
Pour the ½ cup melted butter, 2 large eggs, ½ cup sour cream, ½ cup whole milk, and 1 tsp vanilla extract directly into the well you made in the dry ingredients. Using a rubber spatula or wooden spoon, fold everything together with slow, deliberate strokes until just combined, about 12 to 15 folds. Stop the moment you no longer see dry streaks of flour.
Overmixing is the single most common reason muffins turn out rubbery. A few small lumps in the batter are fine and actually a good sign that you stopped in time.
Step 3: Fold In the Blueberries
Add the 2 cups fresh blueberries to the batter and fold them in with 4 to 5 gentle strokes. You want the berries distributed without crushing them, so use the spatula to scoop from the bottom up rather than stirring in circles.
The batter will look thick and a little shaggy at this point. That is exactly right for a Costco-style muffin with substance to it.
Step 4: Fill the Muffin Cups and Add the Sugar Crust
Divide the batter evenly among the 12 muffin cups, filling each one nearly to the top, about ¾ full. Sprinkle the reserved 2 tbsp granulated sugar evenly over all 12 muffins before they go in the oven.
Filling the cups close to the top is deliberate. It is how you get the tall, domed tops that make these look like bakery muffins. If you fill them only halfway, you get flat, modest muffins.
Step 5: Bake and Glaze the Tops
Bake at 425°F (220°C) for 5 minutes, then reduce the heat to 375°F (190°C) without opening the oven door and continue baking for another 16 to 18 minutes. The muffins are done when the tops are golden brown and a toothpick inserted in the center of one comes out clean or with just a dry crumb or two.
The initial blast of high heat is what drives up that domed top. Let the muffins cool in the pan for 5 minutes, then transfer them to a wire rack. Serve them warm with the crackly sugar crust facing up.
Recipe Tips
- Check your baking powder’s freshness – Drop a small amount into hot water; if it bubbles vigorously, it is still active. Flat baking powder gives you flat muffins no matter what else you do right.
- Room temperature dairy makes a difference – Cold sour cream and cold milk can cause the melted butter to seize into small lumps. Leave them out for 20 minutes before you start.
- Do not open the oven door during the first 10 minutes – The dome forms in the first burst of heat. Opening the door drops the temperature and the tops collapse before they set.
- Measure flour by spooning into the cup – Scooping directly compacts the flour and you end up with 20 to 30% more than the recipe needs, which makes the crumb dense.
Bake times by oven type (425°F / 220°C start, then 375°F / 190°C):
| Oven Type | First Phase | Second Phase |
|---|---|---|
| Standard oven | 5 mins | 16 to 18 mins |
| Convection oven | 5 mins | 13 to 15 mins |
| Dark muffin pan | 5 mins | 14 to 16 mins |
How To Store
- Refrigerate – Store cooled muffins in an airtight container for up to 4 days. The sugar crust softens in the fridge, but the flavor holds well.
- Reheating – Warm a muffin in the microwave for 20 to 25 seconds or in a 300°F (150°C) oven for 8 minutes to bring back some of the original texture.
What To Serve With Costco Blueberry Muffins
A sharp, black coffee cuts through the sweetness nicely and makes the blueberry flavor read as more fruit-forward than sugary. Scrambled eggs alongside turn this into a filling breakfast since the protein balances the carb-heavy muffin without competing with the flavor. A small bowl of plain Greek yogurt with a drizzle of honey also works well, the slight tang mirrors the sour cream in the batter and keeps things from feeling too rich.
Frequently Asked Questions
Can I make the batter the night before?
Yes, but just barely. Mix and refrigerate it for up to 8 hours, covered. Much longer than that and the baking powder loses its punch.
Can I use a jumbo muffin pan instead of a standard one?
Yes. Fill the 6 jumbo cups nearly to the top, start at 425°F (220°C) for 5 minutes, then reduce to 375°F (190°C) and bake for 22 to 26 minutes.
Why did my muffins sink in the middle?
The most likely cause is underbaking. The toothpick test is more reliable than the timer alone, so always check with a toothpick before pulling them out.
Can I freeze these?
Yes. Wrap each cooled muffin individually in plastic wrap, then place in a zip-top freezer bag for up to 2 months. Thaw at room temperature for about an hour.
—
Costco Blueberry Muffin Recipe
Ingredients
Method
- Preheat the oven to 425°F (220°C) and line a 12-cup muffin tin. Whisk the 2 cups flour, 1 tbsp baking powder, ½ tsp salt, and 1 cup granulated sugar together in a large bowl, then make a well in the center.
- Pour the ½ cup melted butter, 2 eggs, ½ cup sour cream, ½ cup whole milk, and 1 tsp vanilla extract into the well and fold with a spatula until just combined, about 12 to 15 folds with no dry streaks remaining.
- Add the 2 cups blueberries and fold in with 4 to 5 gentle strokes.
- Divide the batter among the 12 cups, filling each nearly to the top, then sprinkle the reserved 2 tbsp granulated sugar evenly over all the muffins.
- Bake at 425°F (220°C) for 5 minutes, reduce heat to 375°F (190°C), and continue baking for 16 to 18 minutes until tops are golden and a toothpick inserted in the center comes out clean. Cool in the pan for 5 minutes, then transfer to a wire rack and serve warm with the sugar crust facing up.
