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Leftover Oatmeal Muffins

Tender, gluten-free Leftover Oatmeal Muffins are a great way to use up leftover oatmeal. A simple batter comes together in minutes and solves the question of “what do I do with this leftover breakfast porridge?”!

A wire rack holda leftover oatmeal muffins.

Why You’ll Love Gluten-Free Leftover Oatmeal Muffins

This oatmeal muffin recipe is adapted from my old standby The Fannie Farmer Cookbook. Fannie was the one who guided me through my first baking attempts and can still be relied upon for a good, basic chocolate cake or blueberry muffin or, in this instance, a recipe that is the epitome ofwaste not want not. I love the recipes in Fannie is because they call for simple, real ingredients: nothing fancy, nothing strange.

Fannie Farmer is considered the “mother of level measurements,” meaning that she gave detailed instructions for how to level a cup of flour or precisely measure butter; previous American recipes gave more ambiguous guidance such as telling cooks to measure out a “teacup of milk”. (These other instructions are admittedly more whimsical but I can imagine that a teacup size could vary from kitchen to kitchen … then again, maybe not? Was there a standard teacup size in the 1800s?) That her Boston Cooking-School Cook Book, first published in 1896 and now published under the more familiar Fannie Farmer, is still selling is a testament to the durability of the original recipes.

I adapted this leftover oatmeal muffins recipe to be gluten-free, and it’s packed with whole grain oat flour and cooked oatmeal. A little brown sugar for sweetness, and a handful of chocolate chips or blueberries as you like. It’s not too sweet and makes for a nice, solid little muffin, perfect for a morning snack.

A close up of a leftover oatmeal muffins with blueberries on a wire rack.

What You’ll Need to Make Oatmeal Muffins

Here’s what you’ll need to make this recipe. All the details including ingredient amounts and instructions will be in the recipe card at the end of this post.

  • Oat flour – Whole grain, gluten-free oat flour is perfect paired with cooked oatmeal
  • Brown sugar – You can use lighr or dark brown sugar, or coconut sugar
  • Baking powder – To help the muffins rise
  • Ground cinnamon
  • Salt – I use fine grain sea salt in all of my recipes
  • Milk – Whole milk or 2% milk works fine
  • Egg
  • Butter – Use unsalted butter or melted coconut oil
  • Cooked oatmeal – I use rolled oats but you can use oatmeal made from instant oats as well
  • Add ins – Chocolate chips, fruit, nuts (optional)

Add-In Options

These muffins are fine plain, but I love to dress them up a little bit with 1 cup of dark chocolate chips. Fresh or frozen blueberries or raspberries are also amazing! Or add 1 cup of chopped, toasted walnuts to the batter before baking.

How to Make Leftover Oatmeal Muffins:

  1. Prepare: Heat the oven and line a muffin tin.
  2. Make batter: Whisk together the oat flour, brown sugar, baking powder, cinnamon, and salt. In a separate bowl, stir together the wet ingredients, then combine with the dry mixture.
  3. Bake: Spoon batter into the muffin cups, sprinkle with sugar and bake for about 20 minutes.
A leftover oatmeal muffin on a wire rack.

Tips & Substitution Suggestions

  • Rest the batter – Gluten-free baking always benefits from a rest before a batter or dough is baked so that the flour can hydrate. Let the muffins rest in the tin while the oven preheats for the best results. Read my gluten-free baking tips.
  • Oat flour substitute – You can swap almond flour or sorghum flour, another whole grain gluten-free flour, for the oat flour. More about gluten-free flours.
  • Make them dairy-free – These muffins easily can be made dairy-free if needed! Substitute melted coconut oil for the melted butter, and your favorite non-dairy milk for the milk.
  • Make them refined sugar-free – Instead of brown sugar, you can use maple syrup, honey, or coconut sugar.
  • Make them vegan – Follow the dairy-free substitutions listed above, and leave out the egg.

Storage Options

Place leftover oatmeal muffins in an airtight container and keep them on the counter up to 3 days, in the fridge up to 5 days, or store them in a freezer-safe bag in the freezer for up to 3 months. Thaw in the fridge before eating.

More Gluten-Free Muffin Recipes

Leftover Oatmeal Muffins

Nicole Spiridakis
Tender, gluten-free Leftover Oatmeal Muffins are a great way to use up leftover oatmeal. A simple batter comes together in minutes.
3.50 from 2 votes
Prep Time 5 minutes
Cook Time 20 minutes
Total Time 25 minutes
Course Breakfast
Cuisine American
Servings 12 muffins
Calories 139 kcal


  • 1 ¾ cups oat flour (210 grams)
  • 4 tablespoons brown sugar
  • 1 tablespoon baking powder
  • ½ teaspoon ground cinnamon
  • ½ teaspoon salt
  • ½ cup whole milk
  • 1 egg well beaten
  • 2 tablespoons unsalted butter melted
  • 1 cup cooked oatmeal
  • 1 cup fruit chocolate chips, nuts


  • Heat the oven to 400℉. Line a muffin tin with liners.
  • In a large bowl, whisk together the oat flour, brown sugar, baking powder, cinnamon, and salt. In a medium bowl, stir the milk, egg, and melted butter into the oatmeal, mixing well so that there are no lumps. Pour the liquid mixture into the dry ingredients. Stir in any add-ins if using.
  • Spoon batter into the muffin cups, filling each about 2/3rds full. Sprinkle with more brown sugar if you like. Let the batter rest while the oven heat, then place in the oven and bake for about 20 minutes, or until a tester comes out clean.


Calories: 139kcalCarbohydrates: 23gProtein: 4gFat: 4gSaturated Fat: 2gPolyunsaturated Fat: 0.3gMonounsaturated Fat: 1gTrans Fat: 0.1gCholesterol: 20mgSodium: 215mgPotassium: 125mgFiber: 2gSugar: 7gVitamin A: 154IUVitamin C: 0.4mgCalcium: 91mgIron: 1mg
Did you make this recipe?Let me know in the comments how it went!

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