Keto Peanut Butter Mug Cake – Quick, Cozy, and Low-Carb

A warm, fluffy cake that’s ready in minutes can feel like a small miracle on a busy day. This keto peanut butter mug cake delivers that cozy comfort without the carb overload. It’s rich, nutty, and surprisingly satisfying for such a fast recipe.

You mix everything in a mug, pop it in the microwave, and in about 90 seconds you’ve got dessert. No prep bowls, no oven, and no waiting around.

What Makes This Special

This recipe nails that sweet spot between convenience and real dessert vibes. It uses simple pantry ingredients you probably already have on hand.

It’s also flexible, so you can tweak the sweetness or texture without much fuss. Best of all, it stays low in carbs while still tasting indulgent. If you’re craving something that feels like cake but fits your macros, this is a solid go-to.

What You’ll Need

• 1 large egg – Helps the cake rise and hold together.
• 2 tablespoons creamy, no-sugar-added peanut butter – Look for natural peanut butter with just peanuts and salt.
• 1 tablespoon almond flour – Adds structure without the carbs.
• 1 tablespoon coconut flour – Soaks up moisture and creates a cake-like crumb.
• 1 to 2 tablespoons granulated erythritol or allulose – Adjust for sweetness.
  

  Allulose browns more.

• 1/2 teaspoon baking powder – For lift.
• 1 tablespoon heavy cream – Moisture and richness (use unsweetened almond milk for dairy-free).
• 1/2 teaspoon vanilla extract – Rounds out the flavor.
• Pinch of salt – Balances sweetness and boosts peanut flavor.
• Optional add-ins – A few sugar-free chocolate chips, a pinch of cinnamon, or a swirl of peanut butter on top.

How to Make It

1. Choose the right mug. Use a microwave-safe mug that holds at least 12 ounces. A wider mug gives a more even cook.
2. Mix the wet ingredients. Add the egg, peanut butter, heavy cream, and vanilla to the mug. Whisk with a fork until smooth and glossy.
3. Add the dry ingredients. Stir in almond flour, coconut flour, sweetener, baking powder, and a pinch of salt.
   

   Mix until no dry streaks remain. The batter should be thick but spoonable.

4. Adjust sweetness and texture. Taste a tiny bit of batter and add more sweetener if needed. If it’s too thick, add 1 teaspoon more cream; if too loose, add 1/2 teaspoon more coconut flour.
5. Add mix-ins (optional). Fold in a few sugar-free chocolate chips or dust in cinnamon.
   

   Don’t overmix.

6. Microwave carefully. Cook on high for 60 to 90 seconds. Start with 60 seconds, then add 10- to 15-second bursts. The top should look set but slightly glossy in the center.
7. Rest before eating. Let it sit for 1 to 2 minutes.
   

   It continues to firm up as it cools.

8. Top it off. Add a dollop of whipped cream, a drizzle of warmed peanut butter, or a sprinkle of crushed peanuts for crunch.

Keeping It Fresh

This mug cake is best eaten right away, while it’s warm and tender. If you do have leftovers, cover the mug and refrigerate for up to 24 hours. Reheat gently in the microwave in 10-second bursts to avoid drying it out.

You can also prep the dry mix ahead of time by portioning the flours, sweetener, and baking powder in small jars. When a craving hits, just add the egg, peanut butter, cream, and vanilla and cook as usual.

Health Benefits

– Lower carb load: Using almond and coconut flour keeps net carbs in check compared to wheat flour. That helps you stay on track with a keto or low-carb plan. – Satiating fats and protein: Peanut butter, egg, and cream offer a mix of fats and protein, which help you feel full and satisfied. – No refined sugar: A keto-friendly sweetener reduces blood sugar spikes while still delivering a dessert experience. – Portion control: Single-serve desserts make it easier to enjoy a treat without overdoing it.

Pitfalls to Watch Out For

– Overcooking: A few extra seconds can turn the cake dry or rubbery.

Microwave power varies, so watch closely. – Too much coconut flour: Coconut flour is very absorbent. Even a little extra can make the cake dense. Measure lightly and level off. – Sweetener choice: Erythritol can crystallize and feel cool on the tongue; allulose yields a softer crumb but may brown more.

Pick based on preference. – Peanut butter with added sugar: Many brands sneak in sugar or hydrogenated oils. Read the label to keep carbs low and flavor clean. – Salt balance: Skip the pinch of salt and the cake can taste flat. A tiny bit makes the peanut flavor pop.

Recipe Variations

– Chocolate Peanut Butter: Add 1 teaspoon unsweetened cocoa powder and a few sugar-free chocolate chips. – Cinnamon Swirl: Sprinkle 1/4 teaspoon cinnamon and a dash of nutmeg into the batter.

Swirl a tiny ribbon of peanut butter on top before microwaving. – Peanut Butter Banana Vibe (Keto-Friendly): Use a few drops of banana extract for flavor without the carbs. – Almond Butter Swap: Replace peanut butter with almond butter for a milder, slightly sweeter taste. Add a drop of almond extract to enhance it. – Dairy-Free: Use unsweetened almond milk or coconut milk instead of heavy cream. The texture will be slightly lighter. – Extra Moist: Stir in 1 teaspoon of melted butter or refined coconut oil for a richer crumb. – Crunch Factor: Top with chopped roasted peanuts or a sprinkle of toasted unsweetened coconut.

FAQ

Can I bake this in an oven instead of a microwave?

Yes.

Use an oven-safe ramekin and bake at 350°F (175°C) for about 12 to 15 minutes, or until the center is just set. Check early to avoid overbaking.

How do I calculate net carbs?

Add up total carbs from each ingredient, subtract fiber and sugar alcohols that don’t impact blood sugar (like erythritol). Exact counts will vary based on brands and portion sizes.

What if I’m allergic to peanuts?

Use almond butter, cashew butter, or sunflower seed butter.

Note that sunflower seed butter may turn the cake slightly green due to a natural reaction with baking powder, but it’s safe to eat.

Why did my cake turn out dry?

It was likely overcooked or had too much coconut flour. Next time, reduce the cook time by 10 to 15 seconds and measure the coconut flour carefully. Adding a teaspoon of cream can also help.

Can I make it egg-free?

You can try a flax egg (1 tablespoon ground flaxseed + 2.5 tablespoons water, rested for 5 minutes).

The texture will be denser, but it still works for a quick treat.

What sweetener works best?

Allulose gives a softer, moister crumb, while erythritol keeps things a bit firmer and can taste slightly cool. Monk fruit blends also work; choose what you enjoy most.

Is peanut butter keto?

In moderation, yes. Choose natural peanut butter with no added sugar and mind your serving size to keep carbs and calories in check.

Final Thoughts

This keto peanut butter mug cake is the kind of recipe you’ll use on repeat: fast, reliable, and genuinely satisfying. It’s simple enough for weeknights yet flexible enough to dress up with add-ins and toppings. Keep a few dry mixes ready, and you can have dessert in your hands in under five minutes. When you want something sweet without breaking your routine, this little mug delivers.