Birthday Mug Cake

Annie Lampella @ Ketofocus

By Annie Lampella, Pharm.D.

Published August 28, 2021 • Updated June 2, 2025

Reader Rating
5 Stars (5 Reviews) 8 Comments
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Need to make a quick keto birthday cake but you are short on time? Make this easy and delicious sugar free cake in a mug! Top with a creamy vanilla buttercream frosting and sugar free sprinkles for your birthday celebration.

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Nutrition Facts

2

Servings

645

Calories

67.3g

Fat

5.1g

Protein

1.5g

Net Carb

3.1g

Total Carbs

Disclaimer: The nutrition information provided is an estimate and is for informational purposes only. I am a Doctor of Pharmacy (Pharm.D.); however, this content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician or other qualified health provider before making any lifestyle changes or beginning a new nutrition program.

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Birthday Mug Cake

5 (5) Prep 5m Cook 2m Total 7m 2 servings

Keto Birthday Mug Cake Ingredients

Sugar Free Vanilla Buttercream Frosting Ingredients

  • 1/2 cup unsalted butter, softened
  • 2/3 cup powdered erythritol blend sweetener
  • 2-4 tablespoons heavy cream
  • 2 teaspoons vanilla extract
  • sugar free sprinkles

Step by Step Instructions

1
Make cake batter

To a small bowl, add egg, almond flour, butter, sweetener, coconut flour, baking powder and flavoring.

mixing cake batter in a small pyrex bowl with a fork
2
Bake the birthday mug cake

Spray cooking spray in an 8 oz ramekin or large mug. Add batter to the ramekin and bake in the microwave at 70% for 90-120 seconds or until cake is set and springs back when you lightly touch the top. Oven instructions: Bake in an oven safe ramekin at 350 degrees for 5-10 minutes or until set. Let cake cool while you move onto the frosting

cake batter in a white ramekin next to sprinkles and candles
3
Make keto buttercream frosting

To a medium bowl, add softened butter and cream for 2-3 minutes until light in color and fluffy. Slowly add in powdered sweetener and mix until combined. Add 2-4 tablespoons of heavy cream until desired consistency is achieved. Add vanilla and cream until fluffy.

a spatula with creamy white frosting over a bowl of frosting with candles near
4
Pipe the frosting & add birthday sprinkles

Slide knife around the edges of the ramekin to loosen the cake. Place a plate over the ramekin and flip to place cake on a plate. Add buttercream frosting to a piping bag and pipe frosting on the cake. You can cut your cake in half to make two cakes in order to make a two tired cake. Top with sugar free sprinkles.

piping vanilla frosting on top of a small cake

Similar low-carb recipes

Others who were looking for "Birthday Mug Cake" were also interested in these recipes:

Low Carb Birthday Cake Recipe

a pink candle stuck into a vanilla cake with white frosting
Whether you want to stay keto on your birthday and just want to a make a small cake or you need to make a friend or family member a keto birthday cake, this cake recipe will make the happiest of birthdays. No need to go off your way of eating when you are celebrating. You can still enjoy yummy desserts and a low-carb cake on your special day. And with this cake recipe, we add everything into a small mug or ramekin and bake it in the microwave, so your cake is finished in minutes. (This is also an ideal recipe if you forgot someone’s birthday and need to quickly make them a special cake that looks like you spent hours making.) For this mug cake, we use a combination of almond flour and coconut flour to yield a texture and flavor similar to all-purpose flour. For the secret ingredient that will really turn this cake into a celebration, we add vanilla cupcake flavor drops from One-on-One Flavors. You can get 10% off your order with my affiliate code Ketofocus-10. But don’t worry, you can always substitute with vanilla extract. Top this spongy almond flour based vanilla cake with a creamy sugar free frosting. The keto buttercream recipe is light, fluffy and pairs nicely with our birthday cake. Don’t forget the sprinkles and candles! You’ll be singing ‘Happy Birthday’ in no time with this keto birthday cake recipe.
a two tiered small cupcake birthday cake with a candle

What is a Mug Cake?

A mug cake is a single serve cake that is made in a mug. Technically all the ingredients are mixed in a mug and then it’s baked in the microwave for simplicity. It’s the ideal cake you are really craving cake and just want a slice without having to make an entire keto birthday cake. In this birthday mug cake recipe, I like to mix the cake batter in a small bowl then transfer to an 8 oz ramekin just for presentation. I prefer to remove this vanilla cake from the ramekin and place on a plate. This makes it look like an actual small cake or large cupcake when you add your frosting.

Creamy Keto Buttercream Frosting

No cake is complete without frosting and this recipe for keto buttercream frosting is the creamiest. You only need a few ingredients – butter, powdered sweetener (I use a erythritol blend sweetener), heavy cream and vanilla.  The amount of heavy cream you use will depend on the consistency that you like your frosting to be. For a thicker, denser frosting, use 2 tablespoons. For a lighter frosting, add up to 4 tablespoons. Are you more of a chocolate lover? Try my keto chocolate buttercream frosting instead. This recipe makes a whole batch ideal for a large cake, but you can decrease the recipe by 1/2 or a 1/4 for your keto mug cake.
a mug cake frosted with sprinkles on top

Oven Instructions

No everyone owns a microwave or likes to use them, that’s why I include oven instructions if you want to bake your keto birthday cake in the oven instead of the microwave. Simply preheat your oven to 350 degrees and bake for 5-10 minutes or until cake is set. I recommend baking your cake in a ramekin over a mug as it will bake evenly compared to a mug. Cooking your keto birthday cake in the oven will obviously take longer compared to the microwave, but the results are the same.

Substitutions

Here are some ideas for substitutions if you don’t have ingredients on hand to make this keto birthday cake:
  • Almond Flour: If you are allergic to nuts or don’t want to use almond flour, you can substitute with sunflower seed flour. It measures cup for cup with almond flour and is nut free.
  • Coconut Flour: Don’t worry, this cake will taste like coconut since there are only 2 teaspoons in the entire recipe. But if you wish not to use coconut flour, you can add in 2 more tablespoons of almond flour.
  • Heavy Cream: You can use a nut milk, like almond milk, coconut milk or macadamia nut milk, instead of heavy cream
  • Butter: Looking to make a dairy free keto cake, substitute coconut oil for the butter.
  • Buttercream Frosting: If you don’t like vanilla buttercream frosting, you can substitute with chocolate buttercream or a white chocolate cream cheese frosting or even whipped cream.

Other Keto Mug Cake Recipes

Here are some options for other easy keto cake recipes, whether you are craving chocolate cake or a shortcake, I have a bunch of different cake recipes for you.

Birthday Mug Cake: FAQS

Can I use a different sweetener instead of monkfruit blend?

Absolutely! You can use any sugar substitute you prefer, like erythritol or stevia. Just make sure to adjust the quantity based on the sweetness of the substitute you choose.

How do I store leftover birthday mug cake?

If you have any leftovers, you can store the mug cake in an airtight container in the fridge for up to 2 days. Just reheat it in the microwave for a few seconds before enjoying again!

Is there a dairy-free option for this mug cake?

Yes! You can substitute the butter with coconut oil or a dairy-free butter alternative to make this mug cake dairy-free.

Can I add mix-ins like chocolate chips or nuts?

Definitely! Feel free to fold in some sugar-free chocolate chips or chopped nuts before microwaving for added texture and flavor.

What can I use if I don't have vanilla flavor drops?

You can simply use 1/2 teaspoon of vanilla extract instead. It'll still give you that delicious vanilla flavor!

Nutritional information & Macros

Nutrition Information

Birthday Mug Cake

Servings: 2

Amount Per Serving
Calories 645
Fat 67.3g
Protein 5.1g
Total Carbs 3.1g
Net Carbs 1.5g

A note on accuracy:I calculate all my nutrition using USDA food database values. The actual macros may vary slightly depending on your specific ingredients (marinara brand, exact chicken weight, etc.). For precise tracking, I recommend weighing your portions.
Disclaimer: I'm a Doctor of Pharmacy (Pharm.D.), but this content is not medical advice. Always consult your physician before making dietary changes, especially if you have underlying health conditions.

Annie Lampella, Pharm.D. View My Cookbook

About Annie Lampella, Pharm.D.

Annie Lampella is a Doctor of Pharmacy, mom, and the recipe creator behind KetoFocus. With a B.S. in Genetics from UC Davis and a Pharm.D., she has over 11 years of experience developing family-friendly keto recipes based on the science of human metabolism. She is the author of the Protein Packed cookbook, published by Victory Belt Publishing.

Learn more about Annie →

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8 Comments

  1. I was pleasantly surprised by how moist the texture turned out. Microwave cakes can be tricky but this one was just perfect. I especially loved how simple it was to make with minimal cleanup.

    Reply

  2. I followed the microwave method at 70 percent power for 90 seconds and was impressed with how fluffy and moist it turned out. The combination of almond flour and coconut flour created a surprisingly soft texture for a mug cake. I used vanilla extract instead of the flavor drops and it still had a lovely birthday cake flavor. The buttercream frosting whipped up beautifully after creaming the butter for a few minutes and paired perfectly with the tender cake.

    Reply

  3. Annie, I love this recipe! I’d love to make it into a 13×9 sized cake. Do you happen to have instructions for that? Thanks.

    Reply

    1. I don’t have instructions for that yet. A keto white cake is something that I need to come out with. You can’t just add equal amounts of the same ingredients because you would end up with too many eggs.

      Reply

  4. This is the first keto cake I’ve made that still tasted good 48 hours later. If I want to add cocoa, how much should I add? I don’t want to mess up the liquid/dry proportions. Thanks!

    Reply

  5. Hi!
    I wanted to say I have made this twice now, and it’s so good for a birthday cake replacement. Today I used lemon extract for a twist.
    Thanks for your recipes.

    Reply

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