Microwave Peanut Butter Mug Cake, Low-Carb
A single-serving microwave cake that delivers rich peanut butter flavor in under two minutes. Made with almond and coconut flours instead of wheat, this low-carb dessert uses erythritol for sweetness without blood sugar spikes. The result is dense, moist, and deeply satisfying—with a fudgy crumb and creamy peanut butter topping. Perfect for keto dieters, diabetics, or anyone craving quick dessert without guilt. Serve warm straight from the mug with coffee or almond milk. What sets this apart: it's genuinely low-carb with whole-food fats, no artificial sweeteners beyond erythritol, and ready faster than heating an oven. The two-stage peanut butter application—mixed in and topped—ensures peanut flavor throughout and a melted, indulgent finish.
Ingredients
- 3 tablespoon almond flour
- 1 tablespoon coconut flour
- 1 tablespoon erythritol, granular
- ½ teaspoon baking powder
- 2 tablespoon butter, meltedalmond butter1:1paleotree nut allergypeanuts-freeadds dairy
milder flavor, slightly less moisture
Full guide → - 2 tablespoon peanut butter, low carb, dividedalmond butter1:1paleotree nut allergypeanuts-freeadds dairy
milder flavor, slightly less moisture
Full guide → - 3 tablespoon milk of choice
- 1 egg, beaten
- 1 teaspoon vanilla
Instructions
- 1
In an 8 ounce mug, mix the almond flour, coconut flour, erythritol, and baking powder until well combined.
- 2
Add the melted butter, one tablespoon peanut butter, milk, beaten egg, and vanilla. Stir until smooth.
- 3
Microwave for one minute and thirty seconds or until the top is opaque and cooked through.
- 4
Top with remaining peanut butter and allow it to melt, or melt and drizzle over the cake.
Tips
Stir the batter thoroughly to evenly distribute leavening and prevent dense spots. Lumps of flour won't cook through in 90 seconds, leaving a gritty texture.
Erythritol can crystallize if overheated. Stop microwaving the moment the top loses its sheen; carryover heat finishes cooking. Overcooked mug cakes turn rubbery.
Use a mug with straight sides and no decorative rim; uneven walls create hot spots. Glass or ceramic conducts heat more evenly than thin ceramic.
Good to Know
Refrigerate in the mug, covered, up to 2 days. Reheat 20-30 seconds in microwave before serving.
Mix dry ingredients in the mug up to 12 hours ahead. Add wet ingredients and cook just before serving for best texture.
Serve warm straight from the mug with coffee, tea, or cold almond milk. Pairs well with a small dollop of whipped cream.
Common Mistakes
Skip stirring the dry mix before adding wet ingredients to avoid clumps of baking powder that taste bitter and create dense pockets.
Stop microwaving as soon as the top is opaque; excess time dries out the cake and hardens the crumb.
Use at least 3 tablespoons milk to prevent a dense, gluey texture; too little flour hydration fails.
Substitutions
Vegan Options
Nut-Free Alternatives
milder flavor, slightly less moisture
Full guide →General Alternatives
FAQ
Can I double this recipe in a larger mug?
Yes, use a 16 ounce mug and double all ingredients. Increase microwave time to 2-3 minutes, stopping when the top is opaque. Larger volume requires longer cooking; check at 2 minutes and add 15-30 second intervals as needed.
What if I don't have erythritol?
Monk fruit sweetener works best at 0.7 tablespoons. Stevia requires less (start 1/4 teaspoon) and tastes distinct. Allulose matches 1:1. Regular sugar adds carbs; not recommended for low-carb intent. Avoid maltitol; it causes digestive upset.
Can I freeze the baked mug cake?
Yes, cool completely, cover tightly with plastic wrap, and freeze up to 1 month. Thaw in the refrigerator 2-3 hours or reheat directly from frozen for 45-60 seconds in the microwave. Texture remains moist but slightly denser after freezing.