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4 from 2 votes

Giant Costco Copycat Gluten Free Strawberry Rhubarb Muffins

These are the perfect spring breakfast treat - or snack! - packed with fresh rhubarb and strawberries
Prep Time20 minutes
Cook Time40 minutes
Cooling time15 minutes
Course: Breakfast, Snack
Cuisine: American
Diet: Gluten Free
Keyword: breakfast, costco muffins, easy, giant, gluten free, muffins, rhubarb, strawberry, strawberry rhubarb
Servings: 6 giant muffins
Calories: 500kcal
Author: Amelia Farber

Equipment

  • Six 4-inch round cake pans - link below
  • Small saucepan

Ingredients

  • 4 large eggs
  • 1 1/2 Cups white sugar
  • 1/2 Cup canola oil
  • 2/3 Cup salted butter browned (instructions below)
  • 1 Cup milk
  • 1/2 Cup sour cream
  • 2 1/2 tsp vanilla extract
  • 1/4 tsp ground ginger
  • 2 Cups gluten fre 1-1 flour mix with xanthan gum included (if your mix does not have xanthan gum, add 1 teaspoon of it now)
  • 1/2 Cup sweet rice flour
  • 1/2 Cup packed blanched almond flour
  • 2 3/4 tsp baking powder
  • 3/4 tsp salt
  • 1 1/2 Cups hulled chopped strawberries - plus a few extra for topping into 1/2 inch pieces
  • 1 1/2 Cups peels and chopped rhubarb - plus a few extra for topping into 1/2 inch slices

Instructions

  • First, make your browned butter! In a small saucepan over medium-low heat, melt the 3/4 cup of salted butter and stir constantly until melted and simmering. Continue to simmer, on medium heat, for at least a few minutes, until the popping and hissing sounds have completely subsided (this is the water in the butter burning off – you’ll know once it’s silent). Continue to cook, stirring constantly, until the butter reaches a deep amber color and smells nutty or caramelly. The butter may foam, so keep stirring/lifting up spoonfuls of the butter to see the color. The browned milk solids will foam up in the center of the pan – once it does that- immediately take off the burner and let sit for a few minutes, then pour (scrape ALL of the brown bits – that's the flavor!) into a heat-proof small bowl and let it cool to just above room temp (but not solid).
  • Once your browned butter is cooled but still liquid, make your muffin batter! It will need to rest for 30 minutes before baking. In a large bowl, whisk together the eggs, sugar, oil, melted cooled browned butter (you'll end up with about 1/2 cup of browned butter), sour cream, milk, and vanilla and ginger. Then, in a medium bowl, whisk together the gluten free 1-1 flour mix, sweet rice flour, almond flour, baking powder, and salt, then dump dry ingredients into the wet bowl and whisk until fully combined. Finally, fold in 1 1/2 cups each of the strawberries and rhubarb (save the rest for sprinkling on top of each muffin). Let the batter sit at room temp for 30 minutes.
  • Finally, preheat the oven to 425° Fahrenheit and place your six 4-inch cake pans on a cookie sheet. Spray each pan with cooking spray, then spoon batter into each one evenly (they should be about 2/3-3/4 full) and sprinkle the leftover chopped strawberries and rhubarb on top of each one (just a few pieces on top of each). Bake for 5 minutes at 425 then immediately lower the temp to 350° F (do NOT open the oven door!) and let bake for 25-30 more minutes until the tops spring back with touched. Let cool nearly-completely before turning out and eating!