Giant Costco Copycat Gluten Free Coffee Walnut Muffins

Happy Monday folks! I’m definitely one of those people who love a good, buttery, crumble-top, cinnamon-filled coffee cake, but I also LOVE coffee-flavored baked goods (ie actual coffee cake). And these giant gluten free coffee walnut muffins are exactly that. I’ve tried the coffee + walnut combo once before when making this glorious coffee walnut layer cake filled with toasted walnuts, ganache, and coffee buttercream (it’s the ULTIMATE Monday cake), but really wanted a breakfast muffin that mimicked the flavor. These are super easy, making them perfect as a WHAT-should-I-make-to-get-me-through-Monday bake – even the coffee glaze is super easy! For those of you just joining the GIANT muffin craze over here, we’ve got plenty others if you want to expand your flavor profile for weekday breakfasts, snacks, or weekend treats. So far we’ve made these giant poppyseed muffins, giant blueberry muffins, giant chocolate chip muffins, giant double chocolate muffins, giant banana nut muffins, giant strawberry rhubarb muffins, giant apple streusel muffins, these giant lemon raspberry muffins, and these giant cherry chocolate chip muffins!

Tips for Fantastic Giant Muffins

A few tips for getting these to turn out just like you remember those Costco muffins:

• Use the right-size of pan! Apparently, Costco keeps their giant muffin pans as a trade secret because we can’t find them ANYWHERE on the internet and you can find EVERYTHING on the internet. Bravo, Costco, for a secret well-kept. However, we’ve found a way to crack the code and gone ahead and just used these brilliant 4-inch cake pans because, after careful inspection, we’ve discovered that Costco muffins are exactly 4-inches in diameter! HA! Take that, Costco-bakery-lords. I never thought I’d be regularly using 4-inch cake pans but here we are. I’ll just need to make a bunch of tiny cake recipes next!
• Let your batter REST, per the recipe, for at least 30 minutes. For two reasons: 1) the batter thickens as it rests which is incredibly important for a muffin filled with chunks of things like walnuts (even though walnuts are pretty light)! A thicker batter will help suspend all of the stuff you’ve added all throughout your muffins, ensuring every bite has the perfect ratio of fluffy muffin to add-ins; and 2) something somewhere said that baking powder needs a bit more time to “activate.” Don’t quote me on this, who knows if it’s actually true.
• Don’t over-mix your batter! Muffins need a lot of lift, especially these giant ones, and if you over-mix your batter, you’ll end up with flat or sunken muffins which is no fun.
• Use a good 1-1 gluten free flour mix! We use the Bob’s Red Mill one (the baking mix), though we’ve heard good things about Cup-4-Cup. We’ve only tested this recipe with this one so if you want them to turn out exactly like ours, we recommend snagging a bag of that specific 1-1 gluten free flour.
• Do NOT open the oven door during baking time. Tape it shut if you have to! You can certainly turn on the oven light and peek and the gloriousness that is a set of rising muffins nearly-ready to be devoured, but do not open that door! Opening the door will immediately lower the oven temp and prohibit your muffins from rising correctly. If you’re in the last few minutes of baking and need to test to see if they’re done, open the oven just a tiny bit and reach in and just tap the top of one – if it springs back it’s done, if it presses in like a foam mattress topper, it’s not and needs a couple more minutes!
• These will keep in an airtight container (or in ziplock baggies) for a week or so – and they freeze REALLY well! So if you want to make a batch and save a bunch, put them in a sturdy plastic container or a freezer plastic bag and pop them in there. Then microwave for about 30-45 seconds (from frozen) before eating! I even like popping mine in the microwave for 10-15 seconds from room temp to get them all warm and floofy again before eating.
• GLAZE: glazes are a super easy way to elevate your muffin game. The glazes we use are essentially just powdered sugar and a liquid – in this case, milk + instant coffee. The key with glazes is getting the consistency right – you want to be able to drizzle or pour the glaze, so it needs to be able to move a bit, but you don’t want it to just pour off your muffins completely. You want to get to a thicker consistency (it should be thick when you stir it), that slowly pours when you lift up your stirring spoon. This will ensure that your glaze stays mostly on top of the muffin and that it stays opaque and doesn’t run off in a giant puddle. If your glaze seems to thin and runny, just add more powdered sugar! Vice versa if it seems waaaay too thick and you can’t even get it to pour, add a touch more milk.

Print Recipe

5 from 1 vote

Giant Costco Copycat Gluten Free Coffee Walnut Muffins

These rich muffins are the perfect weekday pick me up, packed with coffee and toasted walnuts!

Prep Time20 minutes mins

Cook Time40 minutes mins

Resting time30 minutes mins

Course: Breakfast, Snack

Cuisine: American

Diet: Gluten Free

Keyword: breakfast, coffee, costco muffins, easy, giant, gluten free, muffins, simple, toasted walnuts, walnut

Servings: 6 giant muffins

Calories: 550kcal

Author: Amelia Farber

Equipment

• Six 4-inch round cake pans (link below to the ones we use)
• Sifter

Ingredients

For the muffins:

• 4 large eggs
• 1 1/2 Cups white sugar
• 1/2 Cup canola oil
• 1/2 Cup salted butter melted
• 1/2 Cup sour cream
• 1 Cup milk
• 3 Tbsp instant coffee
• 2 tsp vanilla extract
• 2 Cups gluten free 1-1 flour mix with xanthan gum added (if it doesn't have xanthan gum, add 1 teaspoon xanthan gum)
• 1/2 Cup sweet rice flour
• 1/2 Cup arrowroot starch
• 2 3/4 tsp baking powder
• 3/4 tsp salt
• 3 tsp espresso powder
• 2 1/4 Cups toasted chopped walnuts instructions below

For the glaze:

• 1 Cup sifted powdered sugar
• 2-3 Tbsp milk
• 1 Tbsp instant coffee
• 1/4 tsp espresso powder

Instructions

• First, toast your walnuts! Preheat the oven to 350° Fahrenheit and line a baking sheet with parchment paper. Spread all of the walnuts on the sheet and then bake for 7-12 minutes or until slightly browned and toasty. Remove and let cool completely before roughly chopping.
• Then make your muffin batter! This will need to rest for 30 minutes before baking. n a large bowl, whisk together the oil, melted butter, sour cream, eggs, vanilla extracts, and sugar until thicker and smooth. In a mug or cup, stir the instant coffee into the milk until dissolved, then add to the batter and mix. Add in the gluten free 1-1 flour, sweet rice flour, arrowroot starch, baking powder, espresso powder and salt and whisk until totally combined and smooth. Fold in 2 cups of the chopped walnuts, then let the batter sit either on the counter for at least 30 minutes before baking (you can let it rest in the fridge for longer if you want).
• Then preheat the oven to 425° Fahrenheit and grease your six 4-inch cake pans with cooking spray and place them all on a cookie tray. Carefully scoop batter evenly into the six pans and place the extra chopped walnuts on top (a few per muffin). Bake for 5 minutes at 425 then immediately reduce the heat (WITHOUT opening the oven door!) to 350° Fahrenheit and continue to bake for 35-40 minutes or until the muffins spring back when pressed with the tip of your finger (try to only open the oven door once and very little to check if they're done). Then remove and let cool for 10-15 minutes before turning out onto a place or cooling rack.
• While the muffins are cooling, make the glaze! In a medium cereal bowl, stir together all of the glaze ingredients until fully combined and very smooth (this may take some working). Check the consistency of the glaze: you're looking for a glaze that can drizzle over the muffins, but doesn't flow too quickly or it will simply run off and not hold on top of the muffins. Add more powdered sugar if it seems too thin/runny.
• Then use a spoon to drizzle the glaze over the muffins, and serve! You can let the glazed muffins sit at room temp for 30-45 minutes for the glaze to harden, then put into zip-top bags and keep in the fridge or freezer for up to a week. Best-served slightly warm, so pop them in the microwave for 10-20 seconds from room temp!

Tag @sisterssansgluten on Instagram if you snap a photo of your muffins!

Food photography and styling by Amelia Farber