Rich and fudgy with deep dark cocoa flavor, mixed in one mug and out of the microwave in 60 seconds. I have made this since I first started creating keto recipes, and it is still what I reach for when I need something sweet right now, with ingredients already in the pantry. What I learned is that it rises fast, so use a mug with room to spare or it overflows. Two minutes from craving to fork. 3.8g net carbs and 9.9g protein.
I have been making this chocolate mug cake since I first started creating keto recipes, and it is still the one I come back to when I need something sweet right now. Not tomorrow. Not after a trip to the store. Right now, with ingredients I already have in the pantry.
The base is simple: one egg, melted butter, almond flour, cocoa powder, and a little coconut flour for structure. That coconut flour matters more than you think. It absorbs liquid and gives the cake body so it does not turn into a puddle. I have tested this ratio dozens of times, and this combination gives you a center that is fudgy without being wet.
The sweetener you pick changes the texture. I use monk fruit for a lighter, more cakey crumb. But I have also made this with allulose, and allulose holds more moisture, so you get a denser, fudgier result. If fudgy is your goal, go with allulose. If you like a little more lift, stick with monk fruit. Either way, the carb count stays the same.
This is also one of those recipes that takes well to add-ins. A teaspoon of peanut butter stirred into the batter before microwaving gives you something that tastes like a low carb peanut butter cup. Sugar-free chocolate chips on top work too. I have even done a dollop of whipped cream after it cools for two minutes, which makes the whole thing feel more like a real dessert. If you like the chocolate chip angle, try my chocolate chip version.
If this is your first time making one of these, use a 12-ounce mug or bigger. Anything smaller and the batter rises over the rim during cooking. I learned that the hard way. A wide, shallow mug also gives you more surface area for crispy edges, which I prefer over a tall narrow one.
For the microwave, 60 to 75 seconds is the window. I check mine at 60 and give the mug a gentle shake. If the center still wobbles, I add 10 more seconds. You want it set but not rubbery. Every microwave runs differently, so the shake test is more reliable than a fixed time.
I keep coming back to this because it scratches the itch without turning into a project. When you want something more involved, my easy keto chocolate cake is worth the extra effort. For variety without the commitment, I rotate between this, my red velvet version, and the pumpkin version depending on my mood.
After 60 to 75 seconds in the microwave, the cake rises right up over the rim of the mug.
Mug or Ramekin?
A ramekin works in the microwave just as well as a mug, and it looks nicer if you are serving someone else. Either way, spray it with cooking spray first so the cake does not stick to the sides.
Everything goes straight into the mug, dry ingredients first, so there is only one dish to wash when you are done.
Which Cocoa Powder to Use
Check the label and use 100% unsweetened cocoa powder. Hot cocoa mixes and some baking blends add sugar, which adds carbs and throws off the count.
Making a Bigger Cake From This Recipe
Yes. Triple or quadruple every ingredient, spread the batter in a greased small baking dish, and bake at 325 degrees. Start checking at 10 to 12 minutes and pull it when a toothpick comes out with a few moist crumbs. It will not be as tall as the mug version, but it slices cleanly once it cools.
How to make it
Grab a 12-ounce or larger microwave-safe mug and add all the dry ingredients first: almond flour, cocoa powder, coconut flour, baking powder, sweetener, and a pinch of salt. Give those a quick stir so the leavening is evenly distributed. Then crack in the egg, pour in the melted butter, and mix until smooth. Scrape the sides down so there are no dry pockets hiding at the bottom.
Microwave on high for 60 seconds, then give it a gentle shake. If the center wobbles, add 10 to 15 more seconds. I find 65 seconds is my sweet spot, but every microwave is different, so trust the shake test over the clock. Once it is set, let it cool in the mug for a minute or two before eating. The same technique works for my birthday version too.
Add all ingredients to a mug or microwave safe small bowl.
2
Mix it
Mix together until combined.
3
Microwave it
Microwave for 60 to 75 seconds or until the cake has risen and is set in the middle. It should not be wobbly when you shake it. Remove from microwave to let cool.
Nutrition
Per serving: 1 mug cake
Calories
382
Fat
34.9g
Protein
9.9g
Total carbs
9g
Net carbs
3.8g
Nutrition is an estimate calculated from the ingredients listed. Brands vary, so check labels if you track closely.
Frequently Asked Questions
Can I bake this in the oven instead of the microwave?
I have done this in a ramekin at 350 degrees for about 12 to 14 minutes. The texture comes out more like a keto lava cake, with crispier edges and a softer center. I actually prefer the oven version when I have the time. Grease the ramekin first or it sticks.
Why did it overflow in the microwave?
Your mug is too small. I use a 12-ounce mug minimum because the batter rises quite a bit from the baking powder and egg. If you only have smaller mugs, split the batter between two of them and reduce the cook time by about 15 seconds each.
Can I make this without eggs?
I have tried it with a flax egg (1 tablespoon ground flax plus 3 tablespoons water, rested 5 minutes) and it works. The texture is denser and a little more crumbly, but it still holds together. I would not skip the egg replacement entirely or you end up with chocolate soup.
Is allulose better than monk fruit for this recipe?
They both work, but I get different textures from each. Allulose holds more moisture, so the cake comes out fudgier. Monk fruit gives a lighter, more traditional crumb. I go back and forth depending on whether I want fudgy or cakey that day. The carb count stays the same either way.
How can I make this dairy-free?
I swap the butter for coconut oil, same amount. The coconut flavor is subtle and actually pairs well with the chocolate. I have also used a dairy-free butter stick and could not tell the difference in the finished cake.
Can I pre-mix the dry ingredients ahead of time?
I measure out the almond flour, cocoa powder, coconut flour, baking powder, sweetener, and salt into small zip bags. When I want one, I dump a bag into a mug, add the egg and melted butter, stir, and microwave. I keep three or four bags in the pantry so there is zero friction between me and chocolate.
Can I make keto chocolate mug cake in the microwave?
Yes, the microwave is exactly how I make this one. Mix everything in a 12 ounce or larger microwave safe mug and cook on high for 60 to 75 seconds. I check at 60 with a gentle shake and add 10 more seconds if the center wobbles. Total time is 2 minutes, and it comes in at 3.8g net carbs.
Can you make a 3-ingredient keto mug cake?
You can find stripped down versions, but I use 8 ingredients here on purpose. The coconut flour absorbs liquid and gives the cake body, and the baking powder gives it lift. Cut those and you lose the fudgy center. Every ingredient earns its spot, and the whole thing still takes 2 minutes at 3.8g net carbs.
What's the best flour substitute for keto mug cake?
Sunflower seed flour is my go-to swap for the 2 tablespoons of almond flour, used in the same amount. If coconut flour is all you have, cut the total to 2 to 3 teaspoons since it absorbs far more liquid. Either way the cake stays fudgy and lands at 3.8g net carbs.
Very good. I melt the butter right in the mug first and add everything else on top, so there’s no second dish to wash. Cocoa mixes in smoother that way too.
Three nights running sounds about right for this one. Try allulose instead of monk fruit if you want it even fudgier, I’ve tested both and allulose holds more moisture, gets the texture closer to a brownie.
Two minutes at midnight is hard to beat. I stir a spoonful of peanut butter in before microwaving when I really want to go there. Comes out like a peanut butter cup.
382 calories for a mug cake could go either way. Here it’s the dark cocoa doing the work, and it delivers. First one I’ve had that doesn’t taste like a negotiated settlement with a chocolate craving.
The coconut flour soaks up liquid the almond flour can’t. I tried just doubling the almond flour and the center came out too wet, didn’t fully set. Stick with both.
I added about 1/4 tsp vanilla, and 1 tsp sour cream, because it was too dry for me at only 45 seconds even with allulose. The additions made the cake nice and moist, but still not anything I’d call “fudgy”. Next time I’ll try 1 tbsp sour cream and see how that works for me. 😊
Hm. Did mine for only 45 seconds, with allulose, and got no fudgy center. It still tastes good, though a little more on the dry side than I like. I live in Colorado Springs, and it’s dry here, so that plus the altitude probably messed me up. Next time I will add a little vanilla extract for more liquid, and maybe even add a teaspoon of sour cream…? I know that can make cakes more moist.
Hi Kimberley, 45 seconds and still dry tells me your microwave runs hot, so I’d go 35 next time and pull it the second the top sets. Sour cream should work fine, though I haven’t tested it. A teaspoon of heavy cream does that job in mine. Was your butter fully melted going in?
I’ve started ending every weeknight with one of these and it’s completely changed how I handle cravings. The two-minute cook time is the thing (I can make it before I even fully commit to wanting dessert and it’s already done). I pre-measure the dry ingredients into little cups on Sundays so the weeknight version is basically just crack an egg and melt some butter. At 3.8g net carbs it fits no matter what the rest of my day looked like.
My daughter is 9 and will eat anything chocolate. She wandered in right when mine came out of the microwave and I tried to tell her it was ‘a grown-up thing with weird flour.’ She took the fork anyway and ate half before I could say another word, then stood there looking at me like I had been hiding something from her. So now I make two mugs and let her think she’s getting the exact same dessert as me. The monk fruit doesn’t register to her at all. Only thing I’d mention is mine came out a little dry the first time because I went the full 75 seconds, so I pull it at 65 now and it’s way fudgier.
Fudgy when you get the timing right (my microwave runs hot, 55 seconds worked better for me), but the monk fruit was a touch too sweet. First bite tasted more like sugar than cocoa. Four stars, tweaking the sweetener next time.
55 seconds is the call for a hot microwave. On the monk fruit, try cutting it to 2 teaspoons next time. The cocoa actually comes through a lot more when the sweetener isn’t competing with it.
I swapped the monk fruit for a tablespoon of allulose and honestly wasn’t expecting much since I barely cook, but this little mug cake came out so dense and fudgy I had to double-check the net carbs. Only 3.8g and it took less than 75 seconds in the microwave. I’m completely hooked.
Making these for my husband and kids this weekend and trying to figure out how to do four at once. Can I mix a big batch and just divide it into four mugs, or does each one need to be measured separately? I’m fuzzy on why there’s both almond flour and coconut flour in there (not sure if the ratios hold when you scale up). Microwave question too: can I run all four mugs at the same time, or does each one need its own full 60-75 seconds? Really hoping these turn out. Nothing beats ending Sunday dinner with everyone getting their own little cake.
My grandmother used to make individual chocolate cakes in ramekins, one per person. Something about the fudgy center took me right back. Didn’t expect 60 seconds in a microwave to do that.
I’ve made plenty of keto desserts that were fine but never quite right, so I wasn’t expecting much from a 75-second microwave cake. Almost didn’t bother. The fudgy center stopped me cold. I stood there eating it straight from the mug thinking there is no way this is 3.8 net carbs. Already on my second one.
I always end up with a rubbery texture when I microwave mug cakes, so I usually pull mine early and finish it in the toaster oven for a couple minutes. Would that still work here or is the full 60 to 75 seconds what gets it to that fudgy texture? Don’t want to mess with a recipe that already sounds dialed in.
Yeah that works. Pull it at about 45 seconds and finish 2-3 minutes at 350 in the toaster oven. You’ll get crispier edges and a softer center, more lava cake than fudgy, but the texture won’t be rubbery.
