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

Warm, soft, and packed with peanut butter flavor, this keto mug cake is the kind of treat you can make on a weeknight without any fuss. It comes together in a single mug, cooks in about a minute, and hits that dessert craving without knocking you off your low-carb goals. The texture is tender and cake-like, not rubbery or dry.

You can dress it up with a dollop of whipped cream or keep it simple and enjoy it right out of the mug. If you love peanut butter and love convenience, this is your new go-to.

What Makes This Recipe So Good

• Fast and easy: From pantry to spoon in under 5 minutes. No oven, no special tools.
• Low-carb and satisfying: Uses almond flour and a keto-friendly sweetener, so you get dessert without the sugar spike.
• Small-batch portion: Built for one, perfect for portion control and late-night cravings.
• Peanut butter flavor: Rich, nutty taste with a soft, moist crumb thanks to the fats in peanut butter and butter.
• Customizable: Add sugar-free chocolate chips, a pinch of cinnamon, or a swirl of cream cheese frosting—whatever fits your mood.

Shopping List

• Creamy peanut butter (no added sugar) – natural or unsweetened works best
• Almond flour – finely ground, blanched for best texture
• Egg
• Butter – or coconut oil for dairy-free
• Keto sweetener – allulose, erythritol, or a blend
• Vanilla extract
• Baking powder
• Salt
• Optional add-ins: sugar-free chocolate chips, a splash of heavy cream, cinnamon, or crushed peanuts

How to Make It

1. Choose the right mug: Use a microwave-safe mug that holds at least 12 ounces.

   This gives the cake room to rise without overflowing.

2. Melt the fat: Add 1 tablespoon butter to the mug. Microwave for about 15–20 seconds until just melted.
3. Stir in the peanut butter: Add 1 heaping tablespoon of unsweetened creamy peanut butter and mix until smooth and glossy.
4. Whisk in the wet ingredients: Crack in 1 egg and add 1/2 teaspoon vanilla extract. Whisk with a fork until fully combined, with no streaks of egg white.
5. Add dry ingredients: Stir in 3 tablespoons almond flour, 1 1/2 to 2 tablespoons keto sweetener (to taste), 1/4 teaspoon baking powder, and a pinch of salt.

   Mix well, scraping sides and bottom so no dry pockets remain.

6. Adjust texture: If the batter seems very thick, add 1 teaspoon heavy cream or water. The batter should be thick but spoonable.
7. Optional upgrades: Fold in 1 tablespoon sugar-free chocolate chips or a pinch of cinnamon.
8. Microwave: Cook on high for 45–60 seconds. Start with 45 seconds; the top should look set and spring back when tapped.

   If needed, add 5–10 seconds at a time. Avoid overcooking—it can turn dry.

9. Rest briefly: Let the cake stand for 30–60 seconds to finish setting. It continues to cook slightly as it cools.
10. Serve: Enjoy straight from the mug or top with a spoonful of whipped cream, a drizzle of warm peanut butter, or a sprinkle of crushed peanuts.

How to Store

If you somehow have leftovers, cover the mug and refrigerate for up to 24 hours. Reheat gently in the microwave for 10–15 seconds, or enjoy cold like a peanut butter snack cake.

For make-ahead convenience, mix the dry ingredients in a small jar and keep on hand. Then add the wet ingredients when you’re ready to cook.

Why This is Good for You

• Low in carbs: Almond flour and keto sweetener replace wheat flour and sugar, keeping net carbs in check.
• Healthy fats: Peanut butter and butter provide satiating fats that help keep cravings at bay.
• Protein boost: The egg and peanut butter offer a solid hit of protein for a dessert.
• Portion control: One mug equals one serving, which makes it easier to stick to your goals.

As always, specific nutrition will vary based on brands and serving size. If you track macros, plug your exact ingredients into a calculator for the most accurate numbers.

What Not to Do

• Don’t overcook it: The line between moist and dry is about 10 seconds in the microwave.

  Start low and add time if needed.

• Don’t use crunchy peanut butter: It can create dry, uneven pockets. Smooth and creamy gives the best texture.
• Don’t skip the baking powder: It’s key for lift and a cake-like crumb.
• Don’t pack the almond flour: Lightly scoop or weigh it. Too much flour makes the cake dense.
• Don’t use a tiny mug: The batter needs space to rise.

  Overflow is messy and cooks unevenly.

• Don’t assume all sweeteners are equal: Allulose tends to make a moister cake; straight erythritol can crystallize. Blend if possible.

Recipe Variations

• Chocolate Peanut Butter: Add 1 teaspoon unsweetened cocoa powder and a few sugar-free chocolate chips. Increase sweetener slightly to balance the cocoa.
• Peanut Butter Swirl Cheesecake: Drop in 1 tablespoon softened cream cheese and swirl lightly before microwaving.
• Salted Peanut Crunch: Sprinkle the top with flaky sea salt and a teaspoon of crushed peanuts after cooking.
• Cinnamon Roll Style: Add 1/2 teaspoon cinnamon to the batter and drizzle with a quick glaze made from powdered keto sweetener and a few drops of cream.
• Dairy-Free: Use coconut oil instead of butter and top with coconut whipped cream.
• Extra Moist: Stir in 1 teaspoon heavy cream or unsweetened almond milk for a softer crumb.

FAQ

Can I bake this in the oven instead of the microwave?

Yes.

Transfer the batter to an oven-safe ramekin and bake at 350°F (175°C) for about 10–12 minutes, or until set in the center. Keep an eye on it because small bakes can go from perfect to dry quickly.

Which sweetener works best?

Allulose gives the most tender, moist texture. A blend of erythritol and stevia also works.

If you use straight erythritol, the cake may be slightly drier—consider adding a teaspoon of cream to the batter.

Is peanut butter keto?

In moderation, yes. Choose an unsweetened, no-added-sugar peanut butter. Watch portion sizes because peanut butter is calorie-dense, even when low in net carbs.

Can I substitute almond flour?

Coconut flour isn’t a 1:1 swap.

If you must use coconut flour, start with 1 tablespoon and add 1–2 teaspoons more liquid to keep it from drying out. The texture will be different but still tasty.

How do I prevent the cake from getting rubbery?

Mix the batter just until combined, don’t overcook, and let it rest for a minute after microwaving. Using allulose or a sweetener blend also helps maintain a softer crumb.

What’s the best way to measure almond flour?

Fluff it with a fork, then spoon into the measuring spoon and level off, or weigh it for accuracy.

Packed almond flour leads to a dense, dry cake.

Can I make it nut-free?

Use sunflower seed butter and a fine, defatted seed flour blend if you have one, though texture will vary. Be aware that sunflower seed butter can turn green when baked due to a natural reaction with baking powder—it’s harmless.

Wrapping Up

This keto peanut butter mug cake is simple, fast, and genuinely satisfying. It uses everyday ingredients, takes a minute to cook, and tastes like a cozy bakery treat without the carbs.

Keep the basics on hand and you can whip one up anytime a craving hits. Once you nail your favorite sweetener and timing, it’ll become a weeknight staple you look forward to. Happy mug-caking!