This oatmeal mug cake is fluffy, tender, just sweet enough to taste like dessert, and healthy enough for breakfast! Think of it like a single-serving oat flour mug muffin that you can whip up in minutes! Delicious served with yogurt or ice cream. Try it with cinnamon for cinnamon roll vibes or pumpkin spice for a festive treat!
This oat mug cake is free from oil, dairy, gluten, soy, coconut, and refined sugar.
Well, I'm at it again with the oat flour. I really can't explain it, but somehow, every time I start experimenting with some sort of baked goods recipe, I just get the most delicious results with oat flour.
Whole wheat flour can sometimes taste a little too "whole-wheat-y" if you know what I mean.
And all-purpose flour can sometimes lean toward gummy when baking without oil (unless you start expanding the ingredient list and making things more complicated).
But I'm a fan of simple.
And the flavor, fluff, and forgiving texture of oat flour just works. For that reason I highly recommend you stick with oat flour for this recipe if possible.
I think you'll love this oat flour mug cake because it's:
- naturally sweetened
- light and fluffy
- made with just 7 simple ingredients
- comforting and spiced like your favorite fall and winter treats
- gluten-free (be sure to use certified GF oats or oat flour)
- ready in minutes
- and healthy enough for breakfast!
Also, I have to say, these photos really aren't doing this mug cake justice. You may not be able to tell, but it's very tender, light, and fluffy.
And true to its name, it's as easy as any mug cake!
Although, for the best results I do recommend mixing wet ingredients in one mug and dry ingredients in a separate mug, just to make sure there are no clumps and that everything is well distributed.
But after that, simply combine wet and dry ingredients, pop this baby in the microwave, press a few buttons, and watch it rise!
RELATED: Love quick and easy mug treats? Try this 5-Minute Microwave Granola!
See the recipe card below for amounts and full instructions. Here's a quick glance at the ingredients you'll need:
- oat flour or rolled oats - currently I'm using this oat flour from Anthony's. If you don't have oat flour, you can start with old fashioned rolled oats and turn them into flour in a blender.
- baking powder - this serves as the leavener and helps the mug cake rise.
- nut butter - any smooth nut butter you like is fine, such as almond, cashew, or peanut. Sunbutter is the best nut-free option.
- non-dairy milk - I used unsweetened almond milk. You could also use coconut, soy, or oat milk.
- maple syrup - the flavor of maple syrup really adds to the tastiness of the oatmeal mug cake. I haven't tried other sweeteners, but a comparable syrup might work. Maple syrup adds moisture, too, so a straight swap with a granulated sweetener won't work.
- spices and vanilla - vanilla extract and your choice of pumpkin spice or cinnamon really make it irresistible!
Oatmeal Mug Cake Instructions
- In a standard, 10-ounce, microwave-safe mug (a larger mug is fine, too), combine the nut butter, milk, maple syrup, and vanilla. Stir really well until it resembles the mixture in the photo above (though the color may be different depending on nut butter used).
- In a separate mug, stir together the oat flour, baking powder, salt, and pumpkin spice or cinnamon.
- Pour the dry ingredients into the wet ingredients, and stir until there's no dry flour.
- Note: my microwave is 1100 watts. Microwave ovens vary. So stay nearby and keep an eye on the mug the first time you try the recipe. Mine come out perfectly when cooked for 70 seconds on high. BUT I recommend starting with just 50 seconds to be on the safe side. Then microwave for another 10 to 20, depending on how much it's rising and whether the center appears firm. If using a smaller, lower wattage microwave you may need to add more time. Do this in 10 to 15 second intervals.
- Let the mug cake rest for 5 minutes before serving.
Haha, "serving." Who are we kidding? We're not serving this to anyone but our own hungry faces.
Can you bake a mug muffin?
Yes, if you prefer not to use the microwave, you can bake the mug cake in a 350 degree oven for around 15 to 18 minutes. Just make sure to use an oven-safe mug, ramekin, or other bowl.
And since this is essentially a muffin batter, I'm sure you can also bake it the same way you normally bake oil-free muffins - whether you use a silicone pan or cupcake liners.
I haven't tested the oat mug cake in a metal muffin pan yet, but it should bake faster than in a mug. So keep a close eye on it in the last few minutes just to be safe.
With such a small, specific recipe like this, even tiny adjustments can make or break it.
So while I would love to be able to say you can sub any flour you like, etc, I really can't say that with confidence.
Each ingredient has a purpose, including the maple syrup and nut butter. Though you may use any nut or seed butter you like, so at least there is some flexibility there!
I tested the recipe once using ¼ cup of King Arthur's gluten-free 1:1 blend, and I'm sorry to have to report, it really wasn't good. It cooked up properly and was edible, but the overall flavor needed some adjustments.
So if you want to go that route, I recommend experimenting with a bit more maple syrup and spice.
For breakfast or a snack, a few spoonfuls of creamy non-dairy yogurt pair perfectly with this oat mug cake. Top it with fresh berries and a sprinkle of your favorite seeds or nuts.
Or if you're in the mood for dessert, serve the mug cake with Vanilla or Pumpkin Oat Ice Cream, extra maple syrup, or some healthy Chocolate Sauce!
If your mug cake has a tough or chewy texture it likely means it's over-cooked. Since all microwave ovens are different, with any mug cake recipe it might take a couple of tries to identify the perfect cook time for your appliance.
Especially with mug cakes, it's best not to substitute a primary ingredient. Of course, it's just a mug cake! So if you feel like experimenting that's up to you. This recipe is written specifically for oat flour and will turn out best if you follow it closely.
More Oat Flour Recipes
- Double-Chocolate Oat Flour Cookies
- Vegan Pumpkin Muffins
- Cherry-Pistachio Muffins
- Oat Flour Pancakes
- Oat Flour Banana Bread
- Apple-Cinnamon Oat Flour Scones
- Oil-Free Chocolate Cake
- Peanut Butter Cookies
- Spiced Tahini Oatmeal Cookies
I hope you enjoy this oil-free oatmeal mug cake recipe. Comment below to share your feedback, and let us know if you experimented with fun flavors, additions, or spices!
Healthy Oat Mug Cake (Oil-Free)
- 1 very full tablespoon smooth nut butter such as almond, cashew, or peanut butter - Sub seed butter if needed.
- 2 tablespoons non-dairy milk, such as unsweetened almond or oat milk
- 2 tablespoons maple syrup
- ½ teaspoon vanilla extract, optional
- ⅓ cup fine oat flour (34 grams)
- ½ teaspoon pumpkin spice blend or cinnamon
- ¼ teaspoon baking powder
- pinch of sea salt
- In a standard, 10-ounce, microwave-safe mug (a larger mug is fine, too), combine the nut butter, milk, maple syrup, and vanilla. Stir well so that the nut butter is fully incorporated.
- In a separate mug, stir together the oat flour, baking powder, salt, and pumpkin spice or cinnamon. Pour the dry ingredients into the mug with the wet ingredients, and stir until there's no visible dry flour.
- Note: this recipe was tested in an 1100 watt microwave. Microwave ovens vary, so stay nearby and keep an eye on the mug the first time you try the recipe. Begin by microwaving on high power for 50 seconds. Then microwave for another 10 to 20 seconds, depending on how much the cake has risen and whether the center appears firm. In my microwave, this recipe comes out just right with a cook time of 70 seconds. If using a smaller, older, or lower wattage microwave you may need to add more time (do this in 10 to 15 second intervals.)
- Let sit 5 minutes, then enjoy! For breakfast it's delicious with plain vegan yogurt and a sprinkle of hemp seeds. Or if enjoying as a dessert, try it with your favorite vegan ice cream, dairy-free whipped cream, and/or maple syrup.
Estimated Nutrition (per serving)
Nutrition information is an estimate and will vary depending on the exact amounts and specific products and ingredients used. We calculate this information using the online calculator cronometer.com.
Saved to try! 🙂 Always looking for good mug muffin recipes. With new food allergies cropping up all the time, first dairy then gluten and most recently eggs, I've tried many! Last few years of working with egg free recipes (for mug muffins) I've noticed that once it looks done it is actually overcooked! For the most moist muffin, the very center should still look a bit too wet / moist. Then let it sit for 5 minutes, and the carryover cooking will finish it! 🙂 Just wanted to add that tip, in case it helps anyone else on this learning curve. 🙂 (Oh! & p.s. Coffee creamer can be used in place of the milk / liquid and can add some some interesting flavors.)
Hi! This recipe is really yummy. I've made it a few times. My problem is I can't get it to rise nearly as much as your picture. I am using a 10 oz mug and following your instructions exactly with all the same ingredients. Do you have any suggestions to help it to get fluffy and rise as much as yours?
Hi Julie, I'm glad you like it! As far as the rise, is there any chance the baking powder you're using is old? It does lose effectiveness over time, so that would be my first guess. It could possibly have to do with differences in microwaves, but if yours is done in about the same amount of time as mentioned in the recipe, then I don't think that would be it.
i'm obsessed! thank you so much for sharing <333
Can u just use regular flour?
You can always experiment, but I think it would probably be better to use a mug cake recipe written specifically for regular all-purpose flour. With recipes like this (small amount, few ingredients), substitutions tend to make a pretty big difference.
Pam in Sacramento
I've made this several times now (used almond butter). It reminds me of a spiced oat muffin. I love it. The texture is perfect and it turns out just right each time.
And even better, I like that I can make and eat ONE muffin, rather than make and eat a dozen.
Thank you, Lori!
This was SO GOOD!!!! I swapped quinoa flour for oat flour, and used 3 T milk and only 1 T of agave nectar (I had just ran out of maple syrup😢). It was a bit dense, but that kinda just made it even more awesome!
Thank you so much for this awesome recipe! 😀
It was super easy to put together, I did find it a bit dry. Maybe a different nut butter? (I used peanut butter) I used half the amount of maple syrup as I didn’t want it too sweet. I’ll try it a little different next time 🙂
Reducing the maple syrup would make it more dry. You could try a spoonful of applesauce next time, to replace the omitted maple syrup. That would help with moisture but not add noticeable sweetness.
I just made this and swapped maple syrup with stevia powder. Just trying to cut down on the calories but i guess that's why it was crumbly. Less moisture. Will give it another try soon.
Also i made it in a ramekin and kept it in the air fryer at 180°C for 15 mins.
Really hit the spot. Added a couple white chocolate chips in the middle. Yum.
This is great! I always get so excited for mug cakes/muffins that sound good and then am disappointed but NOT with this one! It's moist and delicious!
I just made this as a Thanksgiving weekend breakfast treat. I did not have oat flour but had fine oat bran, I used a heaped 1/4 cup as I also added two tablespoons of apple sauce! served with vanilla soya yoghurt, a drizzle of maple syrup and a shake of tiny vegan dark chocolate drops served with large vegan decaf mug of coffee. A delicious autumnal hug in a bowl in my Pj's.
I tried this cake this morning and it was amazing, I love it 😋!!
Do you think it would taste good if I added Nutella next time instead of nut butter?
So glad you enjoyed it, Sally! Yes, I think Nutella will be delicious.
Can I skip the nut butter?
Unfortunately I don’t think that will work well. Having some fat is important for texture. You could experiment with applesauce, banana, or vegan yogurt, but I’m not sure how the results will be.
This turned out so delicious! This cake is my go-to snack from now on 🙂
I tried this recipe exactly as you said. It took 2 minutes in my microwave to get done. It was soo delicious! Very yummy. My husband loved it very much :))
I'm happy to hear that! Thank you for taking a moment to let us know. 😀
This little mug recipe is great! I love PB and syrup from growing up and this hits all those sweet nostalgic notes all the while satisfying my sweet tooth with ZERO refined sugar!🤩 In love! Thank you so much for sharing!
I'm so happy you loved it, Carly. Thanks for sharing!
Was craving cake so pleased to see this in my inbox! Mine only rose half way up the cup and was very dense. Suspecting I used too much almond butter. Will try again tomorrow. Tasty regardless!
Oh, good timing! Hmmm, I hope it rises better next time. Often when I haven't replaced my baking powder in a while that happens. But it might also be a difference in microwaves (did you microwave it?). Glad you like the flavor, Olivia! 😀
This looks like a luscious treat. I'm with you on the oats. After recently becoming sensitive to wheat, I've gone wild for oats! The oat flour works so well in so many recipes. I recently posted a pancake recipe using oats and they are fantastic.
Thank you for sharing the good stuff!
Oh hooray, glad I can help! Mmmmmm, I should do a pancake recipe soon.