Keto Chocolate Mug Cake (90 Seconds, 4g Net Carbs)

This keto chocolate mug cake goes from craving to fork in 5 minutes flat — 90 seconds in the microwave, 4g net carbs, and rich enough to pass for real chocolate cake. It’s the single-serving dessert that has saved more keto diets than any other recipe on this site.

The genius of a mug cake on keto isn’t just speed — it’s portion control. There’s no pan of brownies sitting on the counter whispering at you. You make one, you eat one, you’re done.

Why This Recipe Works

Almond flour and egg give the cake structure without any wheat flour, while melted butter and heavy cream keep the crumb moist — the downfall of most keto mug cakes is dryness, and fat is the fix. A full tablespoon of cocoa delivers deep chocolate flavor, and pulling the cake out at 60-75 seconds leaves the center slightly molten, like a lava cake.

Ingredient Notes and Substitutions

Almond flour: Use blanched, finely ground almond flour — almond meal makes a gritty cake. Do not swap coconut flour 1:1; it absorbs several times more liquid. Sweetener: Powdered erythritol or allulose blend in smoothest. Granular works but can be slightly gritty. Heavy cream: Unsweetened almond milk works in a pinch, though the cake will be a touch less rich. Chocolate chips: Lily’s or ChocZero keep it sugar-free.

The 90-Second Rule

Every microwave is different. Start checking at 60 seconds: the top should look set but still glossy, with a soft center. At 90 seconds it’s fully baked through. Past that, you’re in dry-cake territory — and remember it continues cooking from residual heat for about 30 seconds after the microwave stops.

Storage

Mug cakes are best eaten warm, immediately. If you must save half, cover and refrigerate for up to a day and re-warm for 10-15 seconds — but this cake takes 5 minutes to make, so fresh is always the answer.

Aleta

Keto Chocolate Mug Cake

A rich, fudgy keto chocolate mug cake that cooks in 90 seconds with 4g net carbs. Made with almond flour and cocoa — single-serving dessert with no temptation to overeat.

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Prep Time 3 minutes mins

Cook Time 2 minutes mins

Total Time 5 minutes mins

Servings: 1 mug cake

Calories: 385

Ingredients Method Notes

Ingredients

  

• 3 tbsp almond flour blanched, finely ground
• 1 tbsp unsweetened cocoa powder
• 1.5 tbsp powdered erythritol or allulose
• 1/4 tsp baking powder
• 1 pinch salt
• 1 large egg
• 1 tbsp butter melted
• 1 tbsp heavy cream
• 1/4 tsp vanilla extract
• 1 tbsp sugar-free chocolate chips optional, plus more for topping

Method

 

1. In a microwave-safe mug (at least 10 oz), whisk together the almond flour, cocoa powder, sweetener, baking powder, and salt with a fork.
2. Add the egg, melted butter, heavy cream, and vanilla. Whisk until completely smooth, scraping the bottom and edges of the mug.
3. Stir in the chocolate chips if using.
4. Microwave on high for 60-90 seconds. At 60 seconds the center will be molten; at 90 seconds it will be fully set. Do not overcook — it keeps cooking in the mug for another 30 seconds.
5. Let cool for 1 minute, then top with a few extra chocolate chips or a dollop of whipped cream and eat straight from the mug.

Notes

Microwave wattages vary — start checking at 60 seconds. Overcooking is the #1 cause of dry mug cakes. For an oven version, bake in a ramekin at 350°F for 12-14 minutes. Coconut flour is NOT a 1:1 swap; this recipe is developed for almond flour.

If chocolate and peanut butter is your weakness, our no-bake keto peanut butter fudge is another 5-ingredient dessert that comes together just as easily.

Love This Recipe? Get the Full Cookbook

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Frequently Asked Questions

How many carbs are in a keto mug cake?

This recipe has 9g total carbs and 4g net carbs for the entire mug cake, thanks to almond flour, cocoa powder, and erythritol standing in for wheat flour and sugar.

Why did my mug cake come out dry or rubbery?

It was overcooked. Microwave power varies widely — start checking at 60 seconds and stop while the center still looks slightly underdone. It finishes cooking from residual heat.

Can I make this without a microwave?

Yes. Bake the batter in an oven-safe ramekin at 350°F (175°C) for 12-14 minutes, until the top is set and a toothpick comes out with moist crumbs.

Can I use coconut flour instead of almond flour?

Not as a 1:1 swap — coconut flour absorbs far more liquid. If coconut flour is all you have, use just 1 tablespoon and add an extra tablespoon of heavy cream, though texture will differ.