If you are looking for a dessert that is sweet and tangy, this low-carb mug cake recipe with keto lemon curd is exactly what you are looking for! Not only is this mug cake low-carb it is also sugar-free and gluten-free!

The best part? This mug cake comes in at only 5.9g net carbs!

This mug cake can be made in the microwave, oven, and even air fryer.

low-carb lemon curd cake served in a dish with whipped cream and lemon curd

1-Minute low-carb mug cakes

Sweet and tangy, this keto lemon curd mug cake will blow you away. This is not your typical mug cake, but it still just as easy to make as the rest of them.

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The batter of this mug cake mixes with a homemade lemon curd/custard to give your cake a tangy sponge cake texture you are going to love!

Above view of a lemon curd low-carb mug cake in a dish with whipped cream on the side.

How do you make sugar-free lemon curd?

To make this mug cake you are going to need to have a batch of my lemon meringue filling ready to go. The lemon custard/curd (whichever you call it) takes less than 10 minutes to make and will last in the refrigerator for up to a week, so it is perfect for making in advance.

If you know you won’t use all the lemon curd in a week, you can also freeze it so that it lasts longer. I like to flash freeze the curd in spoonfuls on a lined baking sheet until they are hard, then store the frozen spoonfuls in a zip freezer bag or airtight container.

Freezing the lemon curd in spoonfuls allows you to you easily grab small portion sizes of the keto lemon curd whenever you need it.

How do you make a mug cake batter?

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Making the batter for this mug cake is much like my keto vanilla berry mug cake. Instead of pushing frozen berries into the batter, you will push lemon custard under the batter.

To make the batter, add your butter and cream cheese to your mug and melt it in the microwave for 20 seconds. Next, mix in the remaining batter ingredients except for the lemon curd. That will be added last.

Be sure to scrape the sides and bottom of the mug while you are mixing the batter. When the batter is all mixed, drop a couple of spoonfuls of the lemon curd into the center of the batter. Then use the back of a fork to carefully press the lemon curd down until it is covered with batter.

How do you cook mug cakes?

Tap the mug on the counter to remove any air bubble. Then, cook the mug cake on high in the microwave for 1 minute. If the mug cake isn’t done after 1 minute, let it cook for an additional 20 seconds. My cake only took 1 minute to cook.

You won’t be able to use a toothpick to check for doneness on this recipe since the center is gooey lemon curd. Instead, you’ll need to eyeball the cake for doneness. If the cake parts still look raw, then it probably is and needs a bit longer to cook.

Cooked lemon curd low-carb mug cake in a black mug.

Can I cook a mug cake without a microwave?

If you do not have a microwave (or don’t like to use them), you can still make this mug cake. You will instead want to bake your individual cake in the oven using a cupcake pan or oven-safe ramekin.

Bake the cake at 180C/350F in the oven for 12 minutes, or until it is done.

Lemon Curd Low-Carb Mug Cake in a light blue dish with whipped cream on the side. There is a curled piece of lemon peel on top.

Air fryer

To cook mug cakes in the air fryer you need to find a small baking dish or ramekin to fit inside your air fryer. There must be at least 1 inch on all sides to allow the heat to circulate evenly.

  1. Preheat your air fryer to 180C/350F.
  2. Place the butter in your small baking dish and heat for 30 seconds to 1 minute, or until completely melted.
  3. Make the mug cake following the recipe card below.
  4. Gently lower your baking dish onto the air fryer wire rack. Ensure there is plenty of space between the ramekin dish and the side of the basket.
  5. Cook for 10 minutes, depending on the size of your air fryer and the size of your ramekin or small baking dish.

If you love using your air fryer, I have 101 keto air fryer recipes for you to choose from (chicken, pork, ground beef, salmon, vegetables, and even desserts). Discover how to use your air fryer plus FREE printable air fryer cooking cheat sheets.


Now that your cake is cooked, you are ready to eat it. The lemon custard will absorb into the cake leaving the center glazed with sweet, sticky lemon coating. This means you get that delicious lemon flavor with every bite.

To really dress up your cake, remove it from the mug and top it with whipped cream. If you like lemon, this mug cake is to die for!

A variety of pictures of lemon curd low-card mug cakes. There are picture of cooked cakes and uncooked batter in a mug.

More low-carb dessert recipes

Mockup of Ditch The Carbs Low-carb Sweet Treats eBook

1-Minute Lemon Curd Low-Carb Mug Cake Recipe

How to make a quick and tasty lemon curd mug cake in the microwave
5 from 1 vote
Print Pin Rate
Cuisine: Gluten Free, Grain free, Keto, LCHF, Low Carb, No Sugars, Wheat Free
Keyword: Keto Lemon Curd Mug Cake
Prep Time: 3 minutes
Cook Time: 1 minute
Total Time: 4 minutes
Servings: 1
Calories: 449kcal
Author: Thinlicious.com
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  • Measuring cups and spoons


  • 1 tbsp butter melted
  • 2 tbsp cream cheese full fat
  • 2 tbsp coconut flour
  • 1 tbsp granulated sweetener of choice or more to taste
  • 1 tsp vanilla extract
  • 1/4 tsp baking powder
  • 1 eggs – medium medium
  • 1 tsp lemon zest optional
  • 2 tbsp sugar-free lemon curd/custard


  • Place the butter and cream cheese in your chosen microwavable mug. Microwave on HIGH for 20 seconds.
  • Add the remaining ingredients apart from the lemon curd/custard to the mug and mix well.
  • Drop the lemon curd/custard into the batter. Use the back of a fork or knife to push the curd into the middle of the batter until it is covered.
  • Microwave on HIGH for 1:20 seconds minute. Enjoy!



Please adjust the microwave cooking times according to the strength of your microwave.
My microwave is pretty powerful and only requires 1 minute, but most standard microwaves may require the 1:20 as stated in the recipe.
No microwave? No problem. Simply bake at 180C/350F in a cupcake case or muffin tray for 12 minutes. 


Serving: 1mug cakeCalories: 449kcalCarbohydrates: 13gProtein: 11gFat: 38gSodium: 303mgPotassium: 108mgFiber: 5gSugar: 3g

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