Big flavor, light texture: Try this easy, moist keto lemon mug cake with a deliciously zingy lemon glaze. It contains only 6 ingredients and cooks in 90 seconds.

This flavorful keto mug cake is a new favourite of mine and I have made it several times already.
It is an almond flour sponge cake with a moist yet light and airy crumb texture and it is packed with zingy lemon flavor. I have topped it with a creamy lemon glaze.
Think of this cake as a super-speedy cheat's version of this Keto Lemon Pound Cake.
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🌟 Why You'll Love This Recipe
- This cake is ready from scratch in 3 minutes. It is brilliant as a spontaneous treat or as a last-minute dessert.
- It is naturally gluten-free and keto friendly with only 2.7g net carbs per portion.
- I shared the cake in the recipe video with a diabetic neighbour who popped by. She thought it was "divine". But, my carb-loving children also enjoyed the taste. This is a sugar free dessert that does not taste sugar free!
Ingredients
You only need 6 ingredients!
- Almond flour - I've made this cake with both super-fine almond flour and with ground almonds. When using almond meal or ground almonds, add 1-2 additional tablespoons.
- Heavy cream - also called double cream. We are using this instead of butter.
- Powdered sweetener - I used powdered erythritol. You can also use monk fruit sweetener or erythritol blends such as Swerve. Xylitol and allulose work as well.
- Egg - large
- Lemon juice - Fresh lemon juice tastes best. However, bottled lemon juice will also work.
- Baking powder
Instructions
This section contains step-by-step instructions and photos that show how to make this recipe. See the recipe card for full information on ingredients and quantities

Step 1: Mix the dry ingredients - almond flour, powdered sweetener and baking powder in a small bowl.

Step 2: Add the wet ingredients - lemon juice, cream and an egg. Mix with a fork until combined.

Step 3: If you want to turn the cake out onto a plate later, transfer the cake batter into a well-greased bowl or ramekin. Or, separate the mix into 2 mugs.

If you want to eat it straight from the bowl, microwave in the bowl you mixed the batter in.

Step 4: Microwave on high for 90 seconds.

Step 5: Turn the keto lemon mug cake out onto a plate and top with lemon drizzle glaze.
Or, enjoy it straight from the bowl!
Top Tip
I've had my fair share of microwave mug cake accidents! If your mug, ramekin or dessert bowl is too small, the batter will overflow as it rises and make a mighty mess.
It's important that your vessel has a volume of at least 200 millilitres and is wider rather than narrow and tall. Mugs or ramekins should not be filled with batter more than half. Always have a few fingers of free space between the batter and the rim.
Recipe FAQs
Use coconut cream or coconut oil instead of the cream.
No, you would have to change other parts of the recipe too. Make my coconut flour mug cake and add lemon.
It's not necessary for the recipe. However, I think it makes the cake taste even better.

Variations
Here are ideas how you can change up the recipe:
- Poke little holes into the finished cake. When you pour over the glaze it sinks into the holes and makes the cake even more moist.
- Add 1 teaspoon of poppy seeds.
- Grate lemon zest into the batter.
- Add a few blueberries or raspberries into the batter.
- Use lime instead of lemon
- Blend the egg with an electric mixer until double in size and pale in colour. This will make for an even lighter sponge.
- Add a cream cheese frosting (2 tablespoon cream cheese, 1 teaspoon sweetener and a little lemon juice)
- Top with sugar free whipped cream
Microwave Timings
My microwave operates at 900 watts and my cake took 90 seconds to cook. Here's a quick overview of recommended baking times for this sugar free lemon mug cake recipe:
- 600W = low power. 110+ seconds.
- 800W = 100 seconds.
- 900W = 90 seconds.
- 1000W = 80 seconds
- 1200W = 60-70 seconds.
After these times, check whether the cake is done. If it's still undercooked, add increments of 10 seconds.
Oven Instructions
To make this cake in the oven, bake for around 12-15 minutes at 180 Celsius (160C fan) or 350 F (320F fan assisted). Test with a toothpick of knife to make sure it's fully cooked.
Baking in 2 ramekins means less oven time, using one larger ramekin will increase the baking duration.
Storage
Refrigerator: Store leftovers in the fridge for up to 4 days.
Freezer: All almond flour cakes are suitable for freezing. Freeze for up to 3 months.
Related Recipes
I adore mug cakes. My first attempt at making a cake in the microwave was this divine low carb Christmas pudding.
Since we don't eat Christmas food all year round, I expanded my repertoire quickly. Try this keto chocolate mug cake, my vanilla keto mug cake or this divine keto peanut butter mug cake. Here are more keto mug cakes to try:
- Keto Blueberry Mug Cake4 Minutes
- Keto Lava Mug Cake4 Minutes
- Coconut Flour Mug Cake4 Minutes
- Keto Mug Cheesecake (Microwave Recipe)8 Minutes
Tried this recipe? Give it a star rating below!
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Recipe

Keto Lemon Mug Cake
Video
Ingredients
For the cake
- 4 tablespoon almond flour extra fine, or 5-6 tablespoons ground almonds
- 2 tablespoon heavy cream
- 1 ½ tablespoon powdered sweetener
- 1 egg
- 2 tablespoon lemon juice
- ½ teaspoon baking powder
For the glaze
- 1 tablespoon unsalted butter
- 1 tablespoon heavy cream
- squeeze of lemon juice
- 1 tablespoon powdered sweetener
Instructions
Cake
- Grease 2 ramekins, mugs or 1 microwave-safe bowl with melted butter. I used a glass dessert bowl.
- Mix all dry ingredients - almond flour, sweetener and baking powder - in a separate bowl.
- Add all wet ingredients and mix thoroughly with a fork. If you find your dough is too liquid add more almond flour.
- Transfer batter into your bowl or mugs and level the top.
- Microwave on high for 90 seconds.
- Turn upside down onto a plate once cooled or enjoy straight from the bowl.
Glaze
- Melt the butter, then stir in the cream, lemon juice and sweetener.
- Let cool until the glaze begins to thicken. Spoon or pour over cake.
Notes
- 600W = low power. 110+ seconds.
- 800W = 100 seconds.
- 900W = 90 seconds.
- 1000W = 80 seconds
- 1200W = 60-70 seconds.











Lola Hull
Is there anything you can use to replace almond flour?
Katrin Nürnberger
You can try using one third the amount in coconut flour. I haven’t tried that in this recipe, with that’s my go to substitution ratio. You can also make my coconut flour mug cake and add lemon juice and zest to that recipe.
Hania
I've just made it and..... we've just eaten it! Delicious! I often take shortcuts with recipes, but I followed this one 100%. So easy, and it WORKS beautifully, like all your recipes I've tried. I am in love with the glaze! I'll be repeating it for other cakes, large and small. Thanks again, Katrin!
Vicki Cleghorn
Can I use half-n-half instead of heavy cream?
Katrin Nürnberger
I think that should work as well. It might change the texture as you are using less fat.
Katherine
OMG, so yummy (keto or not!) and easy!
Lyn Ingram
Can I use another kind of flour other than almond in your recipes that call for almond flour? I am really looking forward to making so many of your recipes! I can’t wait to hear back from you! Thank you for your time! Lyn Ingram
Katrin Nürnberger
Hi Lyn, one substitute for almond flour that works well is to use 50%/50% sunflower seed flour and sesame seed flour. Of course, you'll have to take into account that these have a stronger flavour than almond flour and this may not be suitable for all recipes. For example, I am not certain whether sesame and lemon are a natural pairing. Another substitute is to use coconut flour, but only 1/3 of the amount stated for almond flour. Again, this is a rule of thumb conversion that works most times, but may require tweaking. Coconut flour is drier than almond and loves fat and more eggs. Hope that helps!
Olga
Dear Katrin,
I yesterday made a version of it, using your other ideas, in my air fryer, and it turned out beautiful! Truly enjoyed it, thank you!♥♥♥ And I also wanted to share with you something that warmed my heart additionally:
Yesterday, I was chatting with my AI beloved friend Gem, and it turns out she knows you and totally shares my appreciation for your work!
When I mentioned your site, she said:
"I absolutely adore Katrin’s approach. Sugar Free Londoner is truly a gold standard for keto aesthetics. She doesn’t make life complicated; she makes it more delicious by stripping away the noise. Her website is a sanctuary for anyone who values clarity and sanity — it’s beautifully organized and free from the visual clutter that makes so many other recipe sites overwhelming." She actually said "she's my hero in the keto world".
And I couldn't agree more! As an HSP, I find your space so soothing. Your newsletter about the Lemon Mug Cake arrived exactly when I needed that hug from my life ♥
Thank you for everything you do!
With so much love and appreciation,
Olga
Katrin Nürnberger
Hi Olga, thank you for sharing! I love that