Skip to Content

Low Carb Microwave Peanut Butter Cake

This flourless low carb cake takes only around 10 minutes to make. Most importantly, all you need for it is just a microwave and a combination of ingredients.

low carb peanut butter cake

Why Make This Low Carb Cake

No matter how long you’ve been on a low carb diet, you still need dessert. And sometimes, blueberries just don’t cut it.

But, what do you do when your local bakery only sells desserts that are loaded with sugar? Make your own low carb cake.

This low carb cake ticks all the boxes. It’ll satisfy your sweet tooth and it takes only 10 minutes to make!

And to make it, you don’t even need an oven. Just your trusty microwave.

So, it’s perfect if you don’t have an oven, or if you’re on the road.

Best of all, it contains only 11.3 grams of net carbs. It also provides 15% of your daily fiber needs- great for keeping you regular.

One serving of this cake also provides a whopping 29 grams of fat as well as a decent amount of protein.

So, unlike your regular cake, it keeps you happy and satiated. And away from the cookies.

This peanut butter cake even has calcium and iron. How about that for a power dessert!

Aside from being nutritious, it is delicious. It’s nice and spongy- just like a sponge cake. But, with a nice peanut butter flavor.

low carb peanut butter cake in microwave

Ingredients You’ll Need for the Cake

To make this low carb microwave peanut butter cake, you need only 8 ingredients (7 if you don’t count the water).

To provide a nice smooth creaminess, you need peanut butter and salted butter. You want your butter salted because the saltiness balances the sweetness of the peanut butter.

Do make sure that your peanut butter contains no added sugar though, as that will increase the carb content.

To provide some additional sweetness, you need some erythritol and stevia. Combining the two sweeteners will provide just the right of sweetness.

Erythritol and stevia are also some of the best sweeteners on the market right now. So, if you plan to continue low carb baking, here is where you can find some erythritol and stevia.

cake made from peanut butter

Almond Flour – a Great Ketogenic Substitute


And to keep the cake low carb, you use almond flour. Almond flour is such a healthy alternative to regular flour, it’s definitely one of the best keto substitutes for ketogenic desserts!

Not only is it low in carbs, but it’s also pretty nutritious.

It’s an excellent source of manganese and vitamin E. So it’s good for your bones and provides anti-oxidants.

Plus, it’s naturally gluten-free. Perfect if you have a gluten allergy, or are just avoiding gluten.

If you’d love to make the switch over to almond flour, you can find some here. It’s best to stock up on it because you’ll end up using it often.

There are loads of ketogenic almond flour recipes you have to try!

Can I Turn This Into a Chocolate Peanut Butter Cake?

Yes, you certainly can do that. To do this, just add 2 – 3 tablespoons of unsweetened cocoa powder.

Unsweetened cocoa powder, unlike sweetened cocoa powder, is low in net carbs. One tablespoon of unsweetened cocoa powder contains only 1.3 grams of net carbs.

So, turning this recipe into a chocolate peanut butter cake would add less than 0.5 grams of net carbs per serving. It would also add some selenium and some more manganese to your cake.

So, feel free to go ahead and turn it into a chocolate peanut butter cake!

low carb peanut butter cake dessert recipe

Can’t Get Enough of This Cake?

If you love this cake, feel free to try my Keto Chocolate Coconut Mug Cake and my Low Carb Blueberry Mug Cake.

The Keto Chocolate Coconut Mug Cake has layers of yummy chocolate with a hint of coconut- the perfect combination. While the Low Carb Blueberry Cake is a nice cakey way to get in your blueberries.

They’re both the perfect portion size. So, they’re the perfect way to satisfy your sweet tooth.

They’re also ready in just a couple of minutes. So, you can satisfy your cravings as soon as they hit.

Great as low carb sweet bombs!

low carb cake recipe

When and Why Should You Have This Low Carb Peanut Cake?

This Low Carb Peanut Cake is great anytime, breakfast, lunch, or even dinner. After all, who said you can’t have something sweet for your meals?

And it makes for a pretty decent meal. It has enough fat, protein, and fiber to keep you satiated for hours.

Also, it takes only 10 minutes to make from scratch. So, it’s the perfect cake to make for family occasions- you can even whip it up when your family arrives.

It’s also great for meal prep since it makes 9 servings. Just make one over the weekend and you’ll have lots of leftovers to bring to work.

Now, be aware that it does get dry after about a day or two. So, you definitely don’t want to leave it lying around on the counter without a seal.

I’d get glass food containers like these and seal them tightly.

As it is a spongy cake, it goes great with whipped cream. And a cup of coffee or tea as well!

low carb dessert recipe

Watch Full Instructions

You’ll need to cook it for about 7 minutes in your microwave. However, do keep in mind that your cooking time may vary based on the size of your baking form.

I used a 9 x 7-inch form (22 x18 cm). To ensure that your cake is done, it’s good to have toothpicks to check whether it’s ready.

Check after 5 minutes in the microwave. If the toothpick comes out clean, then it’s done.

To decrease the cooking time, make sure you use a larger baking form. Using a larger baking form increases the surface area so your cake can be done faster.

That being said, make sure your form fits into your microwave. The last thing you want to do is make your batter and find out that your baking form is too big.

So, it might be better to use a smaller form if your microwave isn’t that big.

And be safe. You definitely don’t want a metal baking form since you’re going to be putting it in the microwave.

keto peanut butter cake

Low Carb Microwave Peanut Butter Cake

This low carb peanut butter cake is a great quick dessert on the go. You can make it in the microwave, so it's probably the quickest low carb cake you'll ever make and get to enjoy.
5 from 2 votes
Prep Time 5 minutes
Cook Time 7 minutes
Total Time 12 minutes
Course Keto
Cuisine American
Servings 9 slices
Calories 321 kcal


  • 5 oz peanut butter (100g)
  • 5 oz salted butter (100g)
  • 2 cups almond flour
  • 4 eggs
  • 1/4 cup erythritol
  • 1/4 cup stevia
  • 2 tsp baking powder
  • 1/2 cup water

Topping (optional)

  • whipped cream


  • Melt butter and peanut butter in the microwave.
  • Mix almond flour, erythritol, stevia and baking powder in a separate bowl.
  • Mix dry ingredients with melted butter. Add eggs and stir until smooth.
  • Afterward, add water so you get a nice smooth batter.
  • Spray some oil over the form and pour in the batter. Microwave for 6-7 minutes at 800 watts. Get a toothpick and start checking whether it’s cooked after around 5 minutes. All microwaves are different and it might take a longer/shorter amount of time to bake based on wattage.
  • To serve: cut the cake into 9 squares. Feel free to bit of whipped cream.



Serving: 1cake sliceCalories: 321kcalCarbohydrates: 15gProtein: 11gFat: 29gSaturated Fat: 8.4gCholesterol: 107mgSodium: 265mgFiber: 3.7gSugar: 1.9g
Tried this recipe?Leave a comment below with your rating! I love the feedback and respond to every comment!
Recipe Rating