Copycat Costco Double Chocolate Muffins

These Copycat Costco Double Chocolate Muffins are rich, moist, and loaded with chocolate chips in every bite! With a tender crumb and bakery-style tops, they taste just like the beloved Costco muffins only better, because they’re homemade and fresh from the oven.

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Ingredients

Dry Ingredients

• 1 ¾ cups all-purpose flour, spooned and leveled
• ⅔ cup unsweetened cocoa powder, sifted if clumpy
• 1 Tbsp baking powder
• 1 tsp baking soda
• 1 tsp salt
• 1 tsp espresso powder (optional, enhances the chocolate flavor)

Wet Ingredients

• ½ cup unsalted butter, melted and slightly cooled
• 1 ¼ cups granulated sugar
• 2 large eggs, room temperature
• 2 tsp vanilla extract
• ¾ cup buttermilk, room temperature
• ½ cup sour cream, room temperature

Add-Ins

• 2 cups semi-sweet chocolate chips, divided

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Instructions

1. Preheat the oven:
   Preheat to 425°F (220°C) and line a 6-count jumbo muffin pan with jumbo liners. (If using a regular muffin pan, see notes below.)
2. Mix the dry ingredients:
   In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, salt, and espresso powder. Set aside.
3. Combine butter and sugar:
   In a large bowl, whisk the melted (and slightly cooled) butter with sugar until well combined and glossy.
4. Add wet ingredients:
   Whisk in eggs one at a time, then stir in vanilla extract, sour cream, and buttermilk until smooth.
5. Add dry ingredients:
   Gently fold the dry mixture into the wet ingredients until just combined. The batter will be thick. Fold in 1 ½ cups of chocolate chips, reserving the rest for topping. Avoid overmixing to keep the muffins tender.
6. Rest the batter:
   Let the batter rest for 10–15 minutes at room temperature. This step helps create that signature bakery-style rise.
7. Fill the muffin pan:
   Divide the batter evenly among the muffin cups, filling them nearly to the top. Sprinkle the reserved chocolate chips over each muffin.
8. Bake:
   Bake at 425°F for 5 minutes, then (without opening the oven) reduce the temperature to 350°F (175°C) and continue baking for 19–25 minutes.
   The muffins are done when a toothpick inserted in the center comes out with a few moist crumbs (not wet batter).
9. Cool and serve:
   Let muffins cool in the pan for a few minutes before transferring to a wire rack. Enjoy warm or at room temperature!

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Why You’ll Love This Recipe

• Bakery-style muffins at home: Big, domed tops and extra-moist texture — just like Costco’s!
• Double the chocolate: Rich cocoa and melty chocolate chips in every bite.
• Freezer-friendly: Great for make-ahead breakfasts or snacks.
• Crowd-pleaser: Loved by kids and adults alike!

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Tips

• Measure flour correctly: Spoon and level — don’t scoop — to avoid dry muffins.
• Don’t overmix: Stop mixing as soon as the dry ingredients are incorporated.
• Room temperature ingredients: Help the batter mix evenly and rise properly.
• Rest the batter: The 10–15 minute rest improves texture and gives a taller rise.
• Check early: Every oven varies, so start checking for doneness around 19 minutes.

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Variations and Substitutions

• Smaller muffins: Use a regular muffin tin and bake for 15–18 minutes at 350°F after the initial 5-minute high-heat burst.
• Dairy-free: Substitute plant-based butter, non-dairy sour cream, and buttermilk alternatives (1 cup almond milk + 1 Tbsp vinegar).
• Different chocolate: Try milk chocolate or dark chocolate chunks for variation.
• Add-ins: Stir in chopped nuts, peanut butter chips, or white chocolate chips for extra flavor.

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FAQs

Can I make these ahead of time?
Yes! Store muffins in an airtight container at room temperature for up to 3 days or refrigerate for up to 5.

Can I freeze them?
Absolutely. Wrap each muffin individually in plastic wrap, then place in a freezer bag. Freeze for up to 2 months. Reheat in the microwave or let thaw overnight.

Why did my muffins sink?
Usually, this happens if the oven door was opened early or if the batter was overmixed. Make sure to keep the door closed during baking!

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Serving and Suggestions

Serve these muffins warm with a glass of cold milk, a latte, or a cup of coffee. They make an indulgent breakfast, snack, or dessert. For an extra treat, warm a muffin slightly and top it with a scoop of vanilla ice cream or a drizzle of chocolate syrup.