Save I made this on a Tuesday night when I had no dessert in the house and zero patience for preheating an oven. The pantry was nearly bare, but I had peanut butter and a mug. One minute later, I was scraping warm, fluffy cake from the sides of that mug with a spoon, wondering why I'd ever bothered with sheet pans. It became my secret weapon for late-night cravings.
The first time I made this for my roommate, she thought I was joking when I said it would be ready in a minute. She stood by the microwave with her arms crossed, skeptical. When the timer went off and the cake had puffed up like magic, she grabbed her own mug and made one on the spot. Now we keep a running tally of whose mug cake turned out fluffier.
Ingredients
- Creamy peanut butter: This is the backbone of the flavor, so use one you actually like eating straight from the jar.
- Unsalted butter: Melted butter keeps the cake moist and adds richness without making it greasy.
- Large egg: One egg binds everything together and gives the cake its structure and fluff.
- Milk: Any milk works here, dairy or non-dairy, and it loosens the batter just enough to cook evenly.
- Vanilla extract: A small splash deepens the sweetness and rounds out the peanut butter.
- All-purpose flour: Just three tablespoons create the tender crumb without weighing it down.
- Granulated sugar: Two tablespoons sweeten the cake without turning it into candy.
- Baking powder: A quarter teaspoon makes the cake rise in the microwave like a tiny miracle.
- Salt: A pinch balances the sweetness and makes the peanut butter taste more like itself.
Instructions
- Mix the peanut butter and butter:
- In a large microwave-safe mug, stir together the peanut butter and melted butter until the mixture looks smooth and glossy. This step sets up a rich base that coats every bite.
- Add the wet ingredients:
- Crack in the egg, pour in the milk and vanilla, then whisk everything with a fork until no streaks remain. The batter should look creamy and unified.
- Fold in the dry ingredients:
- Sprinkle in the flour, sugar, baking powder, and salt, then stir gently until just combined. Overmixing makes the cake tough, so stop as soon as you no longer see dry pockets.
- Microwave until set:
- Cook on high for 60 to 75 seconds, watching through the window as the cake puffs up and the center firms. Every microwave is different, so start with 60 seconds and add time if needed.
- Cool and enjoy:
- Let the mug sit for a minute or two so you dont burn your tongue. Then grab a spoon and dig in straight from the mug.
Save One night I made this and topped it with a scoop of vanilla ice cream while it was still warm. The ice cream melted into the crevices and turned the whole thing into a molten peanut butter sundae. My partner walked into the kitchen, saw me eating it straight from the mug, and asked if I was okay. I was more than okay.
How to Know When Its Done
The cake should rise up in the mug and look set in the center, not wet or shiny. If you gently press the top with your finger, it should spring back. The edges might pull away from the sides of the mug slightly, which is a good sign. If the center still looks liquidy, give it another 10 seconds and check again.
What to Do If You Dont Have Peanut Butter
You can swap in almond butter, cashew butter, or even sunflower seed butter if you have a nut allergy. The flavor will shift, but the texture stays soft and cakey. I once used tahini because it was all I had, and it tasted like a sesame halva cake, which was a happy accident.
Toppings and Mix-Ins
Once you master the base, this becomes a blank canvas. I stir in chocolate chips before microwaving, or drizzle honey on top while its still warm. A spoonful of jam in the center turns it into a peanut butter and jelly dessert, and a pinch of cinnamon in the batter makes it taste like a snickerdoodle.
- Try a handful of mini chocolate chips stirred into the batter before cooking.
- Drizzle with maple syrup or a spoonful of Nutella right after it comes out.
- Top with sliced banana and a sprinkle of sea salt for a grown-up twist.
Save This little mug cake has saved me from sad snack nights more times than I can count. Keep the ingredients on hand, and youll never be more than two minutes away from something warm and sweet.
Cooking Questions
- → Can I use non-dairy milk for this cake?
Yes, you can substitute almond, oat, or other non-dairy milks without affecting texture significantly.
- → How do I avoid overcooking the cake in the microwave?
Microwave on high for about 60 to 75 seconds and watch for the cake to rise and center to set; avoid cooking longer to prevent dryness.
- → What variations can I add to enhance flavor?
Try mixing in chocolate chips, drizzling honey, or serving with a scoop of ice cream for added richness and texture.
- → Is it possible to make this gluten-free?
Yes, replace all-purpose flour with a 1:1 gluten-free flour blend for a gluten-free version.
- → How should I store leftovers if any remain?
Since this is a single-serving cake best enjoyed fresh, store any leftovers covered in the fridge up to one day and reheat briefly before eating.