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4-Ingredient Keto “Peanut” Butter Mug Cake

Louise Hendon | September 16
4-Ingredient Keto

Mug cakes are all the rage and for good reason. You want your cake, and you want it now. Try this 4-ingredient keto “peanut” butter mug cake the next time you want an indulgent treat.

Watch this video to see how simple it is to whip up a Keto mug cake in minutes.

Simple Keto Ingredients

One of the best parts of this mug cake is that it doesn’t have a laundry list of things you need to buy to make it.

It’s short, sweet, and simple.

Like most mug cakes, you’ll need an egg. A small or medium-sized egg works well. If the egg is too large your little cake will taste…well, like eggs.

Instead of flour (this is keto, after all) I used baking powder to give this cake a boost and help it rise properly.

To make it cake-like instead of bread-like, you’ll need to add sweetener. Erythritol and stevia are two of my go-to options for keto, and I chose to combine them in this recipe.

It really doesn’t take much of either ingredient. Just a tablespoon of erythritol and a pinch of stevia does the trick.

Finally, instead of peanut butter, I used almond butter.

Why Not Use Peanut Butter?

On the surface, it seems like peanut butter is a pretty good option for keto. High in fat, and low in carbs, it checks some important boxes.

It also has a decent amount of protein and is a good source of vitamin E, niacin, magnesium, and more. It’s also noticeably cheaper than other nut butter.

Unfortunately, there is a “but” coming.

If you’re up on paleo, you probably know that peanuts aren’t nuts at all, but legumes, which aren’t great for you.

But a more compelling reason to skip peanut butter is aflatoxin, a chemical often found on peanuts.

Eating aflatoxin is linked to liver cancer in adults, which is a pretty good reason to steer clear.

The FDA monitors the level of aflatoxin in peanut products and isn’t shy about pulling food off the shelf that exceeds their limits. But let’s be honest, they can’t check everything.

There’s another malicious lurker in peanuts: peanut agglutinin. This sinister stuff fights digestion and has been found to penetrate the gut lining.

If you’re still not convinced, I wrote an entire article about peanut butter and keto. And another one about the broader world of nuts.

Bottom line is, if you’re going to eat nuts on keto, there are better choices than peanuts (which are legumes anyway).

Free Ketogenic Meal Plan

If you enjoyed my thoughts on peanut butter or just liked this mug cake recipe, be sure to check out my FREE seven-day meal plan.

It takes the guesswork out of what to eat and lets you focus on enjoying the food.

4-Ingredient Keto "Peanut" Butter Mug Cake #keto

4-Ingredient Keto "Peanut" Butter Mug Cake #keto

4-Ingredient Keto “Peanut” Butter Mug Cake

  • Author: Louise Hendon
  • Prep Time: 3 minutes
  • Cook Time: 2 minutes
  • Total Time: 5 minutes
  • Yield: 1 serving 1x
  • Category: Dessert
  • Cuisine: American


  • 1 egg, whisked
  • 1/4 cup nut butter of your choice (we suggest almond butter or hazelnut butter instead of peanut butter)
  • 1 Tablespoon (12 g) erythritol + dash of stevia
  • 1/4 teaspoon of baking powder (1 g)


  1. Blend the egg, nut butter, sweetener, and baking powder together.
  2. Place into a mug or cup and microwave on high for 2-3 minutes.


All nutritional data are estimated and based on per serving amounts.

Net Carbs:  5.6 g


  • Calories: 455
  • Sugar: 2.8 g
  • Fat: 39.5 g
  • Carbohydrates: 12 g
  • Fiber: 6.4 g
  • Protein: 19.4 g
Louise Hendon

Louise holds a Bachelors and Masters in Natural Sciences from Cambridge University (UK). She attended Columbia University for her JD and practiced law at Debevoise & Plimpton before co-founding Louise's Foods, Paleo Living Magazine, Nourishing Brands, & CoBionic. Louise has considerable research experience but enjoys creating products and articles that help move people just a little bit closer toward a healthy life they love. You can find her on Facebook or LinkedIn.