Square Blueberry Oatmeal Muffins

Hearty oats and juicy blueberries make these Blueberry Oatmeal muffins are perfect morning snack. Ready in less than 30 minutes, they can be baked fresh for breakfast, or a grab-and-go snack.

Close up of square blueberry oatmeal muffin on a white plate with the edges of three more square blueberry muffins in the background.

What Makes These Blueberry Oatmeal Muffins Different?

The biggest difference is the shape of the muffins. This recipe is baked in a brownie pan making these muffins square instead of round like traditional muffins.

These muffins are not baked in muffin paper cups either. The pan is lightly greased before filling which helps give the muffins a crispier edge.

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Ingredients for Square Blueberry Oatmeal Muffins

Ten ingredients make up this recipe. These are ingredients I usually always have on hand.

  • Oats. For this recipe, quick oats are used.
  • Milk. Any milk you have on hand will work with this recipe. I have used all types of milk, from skim to whole, with great results.
  • White Sugar.
  • All Purpose Flour.
  • Baking Soda.
  • Salt.
  • Egg.
  • Vanilla Extract.
  • Melted Butter.
  • Frozen Blueberries.

Why Soak The Oats In Milk?

For this recipe, the oats are soaked in milk for 10 minutes before mixing in the remaining ingredients. If you add oats to the batter without soaking them, the batter becomes dry and possibly tough.

The oats will soften as they absorb the milk, making the muffin batter creamier. This also makes for a moister muffin in the end.

Can This Recipe Be Doubled?

The recipe for these Square Blueberry Oatmeal Muffins makes only six muffins. But if you are looking to make a dozen muffins the recipe can be doubled easily.

Substitutions And Add-Ins For Square Blueberry Oatmeal Muffins


These muffins have ingredients that can be easily swapped out.

The oats in the recipe are quick oats. But I have used rolled oats (old-fashioned oats) as well as minute oats. The difference is in the texture of the muffins. Rolled oats are larger and will affect the results. You can also pulse the oats in a blender for a few seconds to get a similar texture to quick oats.

This recipe has also been made with almond milk, cashew milk, and oat milk in place of the milk. I have had great results with all these.

Vegetable oil can be used to replace melted butter in this recipe.

Fresh berries can also be used in place of frozen.


To add a touch more sweetness to these muffins, a sprinkle of coarse sugar can be added to the tops before baking.

If you’re looking to add crunch to this recipe, chopped walnuts or slivered almonds make great choices.

How To Store Muffins

Square Blueberry Oatmeal Muffins can be stored in an air-tight container for up to 3 days. Store them at room temperature.

They can also be stored in the freezer for up to a month. Thaw at room temperature before serving.

Close up of square blueberry oatmeal muffin on a white plate with the edges of three more square blueberry muffins in the background.

Square Blueberry Oatmeal Muffins

Hearty oats and juicy blueberries make these Square Blueberry Oatmeal muffins are perfect morning snack.
Prep Time 15 minutes
Cook Time 22 minutes
Total Time 37 minutes
Course Breakfast, Snacks
Cuisine American, Canadian
Servings 6 muffins


  • 6 hole brownie pan


  • ½ cup quick oats
  • ½ cup milk
  • ½ cup white sugar
  • 1 tsp vanilla extract
  • 1 egg
  • 1 cup all-purpose flour
  • ½ tsp baking soda
  • ½ tsp salt
  • 3 Tbsp butter, melted and cooled
  • ¾ cup frozen blueberries


  • In a medium-sized bowl, soak oats in milk for 10 minutes.
  • Preheat oven to 375℉ and grease brownie pan.
  • Add egg, vanilla, and white sugar to the oats after soaking.
  • In a small bowl, whisk together flour, baking soda, and salt.
  • Add dry ingredients to the oats along with the melted butter.
  • Stir until almost completely blended.
  • Fold in blueberries.
  • Fill prepared pan with batter
  • Bake for 20-23 minutes or until fully baked in the centres. Rotate pan halfway through baking to ensure even baking.
  • Allow to cool for 5 minutes in pan before transferring to a cooling rack to finish cooling.


Brownie pan used for this recipe can be purchased on Amazon.
A 6 cup muffin pan can also be used. 
Keyword blueberries, breakfast, muffins


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