This peanut butter mug cake is a super indulgent, super easy dessert. And it proves the well-known fact that life is just BETTER with peanut butter!

I love mug cakes, because they deliver almost instant gratification.
There you are, thinking: "Wouldn't it be lovely to eat something sweet right now?" So you stir up a few ingredients and stick it in the microwave.
And less than five minutes later you're tucking into a warm, comforting keto peanut butter mug cake. It's almost too good to be true!
I have a few delicious mug cake recipes on my website already - check out this sugar free lemon mug cake, my keto chocolate chip mug cake and this coconut flour mug cake.
All equally gorgeous, ridiculously simple and delightfully sugar-free. Take your pick according to your craving of the day!
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Ingredients
I made the recipe several times before it was perfect.
First, I made a totally flourless peanut butter mug cake. I only used peanut butter, egg, sweetener and a little bit of baking powder.
This combo was a bit firm for my taste, especially once cooled. (Incidentally, it makes incredibly crunchy keto peanut butter cookies).
To fluff it up, I added coconut flour and a good measure of heavy cream.
These additions make the mug cake taste like a REAL, moist cake. Yum.
Last but not least, I also added chopped dark chocolate!
Which Peanut Butter Is Best?
Try and source peanut butter that is unsweetened. Good peanut butter only needs to contain 1 ingredient - peanuts.
Both smooth and crunchy peanut butter work in this recipe - use whichever you prefer!
How Many Carbs In Peanut Butter?
Even though peanuts are technically a legume, they are high in fat and low in carbs - just like nuts. This makes pure peanut butter a popular keto food. One tablespoon contains 3.2g net carbs.
Not all peanut butter is keto-friendly. Always read the ingredients when you shop. Some brands add sugar or inflammatory vegetable oils.
Which Chocolate Chips To Use?
The chocolate chips are optional - the mug cake tastes just as good without them. However, we all know that chocolate and peanut butter are a dream team!
I used chocolate with 90% cocoa solids for my cake, which I chopped. If possible, your chocolate should contain at least 85% cocoa solids.
You can also use sugar free chocolate chips such as Lily's (available in the US). Or you make your own sugar free chocolate chips!
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.

1.) Put all ingredients into a mug.
2.) Mix the ingredients with a fork inside the cup.
3.) Stir in the chopped chocolate.
4.) Microwave until the cake is cooked and starts to peel away from the mug.
Enjoy as is or top with sugar free whipped cream, peanuts and shaved chocolate.
Microwave Tips
Choose a tall vessel for microwaving. You want to have at least 3 fingers space at the top. Mug cakes have a habit of rising and can spill over the top.
To avoid a mess, pause the microwave to check after about 50 seconds. If necessary, continue cooking the cake in 10-second bursts.
This will prevent spillage as you’re giving the cake time to sink back down in between.

Recipe Variations
Possible add-ons for this cake: ½ teaspoon vanilla extract or 1 teaspoon cinnamon.
To make this mug cake dairy-free, use coconut cream in place of the double/heavy cream.
If you prefer cakes with almond flour, use ¼ cup or 4 ½ tablespoons of almond flour instead of coconut flour.
Ran out of peanut butter? You can use almond butter or any other nut butter in this recipe.
This chocolate peanut butter mug cake is VERY FILLING. Personally, I think it’s perfect for sharing. If you don’t want to spoon from the same cup, simply divide the mix between 2 ramekins.
Oven Instructions
Don't have a microwave? Simply cook the mug cake in the oven. Use oven proof ramekins and bake at 180 Celsius (350 Fahrenheit) for 10 -12 minutes.
Storage
You can store this mug cake with peanut butter in the fridge for up to 3 days or even freeze it.
If you decide to divide the batter between 2 ramekins and eat one cake straight away and one the next day, I recommend that you refrigerate the second portion as a batter. Then, cook it straight before eating.
Tried this recipe? Give it a star rating below!
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Recipe

Keto Peanut Butter Mug Cake
from Sugar Free LondonerNote: The servings slider only changes the first amount in each line and not any subsequent amounts. Please make your own calculations where necessary.
Ingredients
- 1 ½ tablespoon coconut flour
- 2 tablespoon peanut butter
- 1 ½ tablespoon powdered sweetener add an additional ½ teaspoon if you have a sweet tooth
- 3 tablespoon double / heavy cream or coconut cream for dairy free
- 1 egg medium
- ¼ teaspoon baking powder
- 1 tbsp dark chocolate, chopped or sugar free chocolate chips optional
Instructions
- Mix all ingredients in a tall glass or cup, using a fork. Fold in the chocolate last, if using.
- Microwave on high for about 90 seconds.
Char
This is just lush! I’ve been on keto for eight months and found it really boring until I discovered your website. I’m so relieved that I did. Your recipes are awesome and have helped me so much to remain with this lifestyle choice, which I switched to as I have seizures. Super grateful for all the tips, thorough recipes and really good ingredient advice.
Lionel Velez Jr
Can you make it with almond flour?
Katrin Nürnberger
It should work with around 4 tablespoons of almond flour.