Save I was staring into the pantry at 11 p.m., craving something sweet but too tired to preheat an oven. That's when I spotted the peanut butter jar and thought, why not just make a cake in a mug? One minute in the microwave later, I was eating warm, fluffy peanut butter heaven straight from the cup. No mixer, no mess, no regrets.
The first time I made this for my roommate, she watched skeptically as I stirred everything in a mug. When I pulled it out of the microwave, puffed and golden, she grabbed a spoon before I could even let it cool. Now she makes one every Sunday night while catching up on her shows.
Ingredients
- Creamy peanut butter: This is the backbone of the cake, so use one you actually like eating by the spoonful.
- Unsalted butter, melted: Adds moisture and richness without making the cake greasy if you measure carefully.
- Large egg: Binds everything together and gives the cake structure so it doesn't collapse into pudding.
- Milk: Any kind works, dairy or plant based, just make sure it's at room temperature so it blends smoothly.
- Vanilla extract: A small splash deepens the flavor and makes the whole thing smell like a bakery.
- All purpose flour: Just enough to hold the cake together without making it dense or heavy.
- Granulated sugar: Sweetens the cake and helps it rise into that perfect fluffy texture.
- Baking powder: The magic ingredient that makes the cake puff up in seconds.
- Pinch of salt: Balances the sweetness and makes the peanut butter taste even more intense.
Instructions
- Mix the base:
- Combine the peanut butter and melted butter in a large microwave safe mug, stirring until smooth and glossy. This step ensures no clumps hide in the batter later.
- Add wet ingredients:
- Crack in the egg, pour in the milk and vanilla, then whisk everything with a fork until fully blended. The mixture should look pale and slightly frothy.
- Fold in 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 the streaks disappear.
- Microwave:
- Cook on high for 60 to 75 seconds, watching as the cake rises up the sides of the mug. It's done when the center looks set, not wet or jiggly.
- Cool and serve:
- Let it sit for a minute or two so you don't burn your tongue. Then grab a spoon and dig in straight from the mug.
Save One rainy afternoon, I made this for my nephew who was sulking about a canceled playdate. He watched the mug spin in the microwave like it was a science experiment, then his eyes went wide when it puffed up like a soufflé. We ate it together with a scoop of vanilla ice cream melting into the warm cake, and suddenly the rain didn't matter anymore.
Topping Ideas
I've tried this plain, with chocolate chips melted on top, drizzled with honey, and crowned with a scoop of ice cream. The chocolate chips are my favorite because they get all melty and gooey, turning every bite into a peanut butter cup situation. A spoonful of jam or a sprinkle of sea salt also works if you want to get fancy.
Flavor Swaps
Natural peanut butter makes the cake taste deeper and less sweet, almost like the filling of a fancy candy bar. Almond butter or sunflower seed butter work too if you're avoiding peanuts, though the texture will be slightly denser. I once stirred in a pinch of cinnamon and it tasted like a peanut butter cookie in cake form.
Common Mistakes to Avoid
The biggest mistake is overcooking, which turns the cake rubbery and dry instead of soft and tender. Another one is using a mug that's too small, which leads to batter erupting all over the microwave like a volcano. Finally, don't skip the minute of cooling time, because molten peanut butter cake straight from the microwave is hotter than lava.
- Check your mug size before you start mixing anything.
- Stop the microwave as soon as the center looks barely set.
- Let it cool just long enough to avoid burning your mouth.
Save This little mug cake has saved me from late night snack regret more times than I can count. It's proof that sometimes the best desserts are the ones you can make in your pajamas without planning ahead.
Recipe FAQ
- → What makes this peanut butter dessert fluffy?
The combination of baking powder and egg helps the mixture rise quickly in the microwave, creating a light and airy texture.
- → Can I use dairy-free milk alternatives?
Yes, almond or oat milk can be used to maintain creaminess while keeping it dairy-free.
- → How long should I microwave the mixture?
Microwave on high for 60 to 75 seconds until the center is set but not overcooked to keep it moist.
- → Are there ways to enhance the flavor?
Adding chocolate chips, a drizzle of honey, or a scoop of ice cream can elevate the rich peanut butter taste.
- → Is this dessert suitable for gluten-free diets?
Substitute all-purpose flour with a gluten-free blend to make the dessert gluten-free while maintaining texture.