Chocolate Peanut Butter Mug Cake

So you’re craving something sweet but too lazy to preheat the oven, measure twelve ingredients, and wait 40 minutes for a cake to rise? Same. Enter the chocolate peanut butter mug cake: a gooey, fudgy, peanut‑swirled dream you make in a mug, in the microwave, in about 5 minutes flat (3 of those are you looking into the microwave window like it’s TV). This is the late‑night snack that understands you. It’s single‑serve, low drama, high payoff, and yes—you get melty peanut butter pockets. Grab a mug and let’s make chocolate happen.

Why This Recipe is Awesome

A full cake is a commitment. A mug cake is a fling—with benefits. Rich cocoa + peanut butter = classic candy bar vibes without the wrapper guilt. You mix, microwave, and eat from the same mug, so cleanup is basically a rinse. It’s idiot‑proof. Even I didn’t mess it up, and I once forgot sugar in brownies. Make it as gooey or as cakey as you like by tweaking microwave time. Plus, it’s endlessly riffable: protein powder? Sure. Vegan swap? Easy. Nutella swirl? Say less.

Ingredients You’ll Need

(Serves 1 hungry human. Double only if you’ve got 2 mugs and self‑control.)

4 tbsp all‑purpose flour (about 30 g)
2 tbsp unsweetened cocoa powder
2 tbsp sugar (or coconut sugar, or brown sugar for caramel notes)
1/4 tsp baking powder
Pinch salt
3 tbsp milk (dairy or non‑dairy)
1 tbsp neutral oil or melted butter
1 tbsp creamy peanut butter (natural or not; see Tips below)
1/4 tsp vanilla extract
1–2 tbsp chocolate chips or chopped chocolate (optional but recommended)
Optional add‑ins: pinch instant espresso (boosts chocolate), cinnamon, flaky salt for topping

TIP: Use a microwave‑safe mug that holds at least 12 oz (350 ml). The batter rises fast and needs headroom.

Step-by-Step Instructions

Prep the mug. Lightly oil or spray the inside if you want easier cleanup. Not required, but mug scrubbing is no fun at midnight.
Dry mix. Add flour, cocoa, sugar, baking powder, and salt to the mug. Stir with a fork until the cocoa disappears into the flour (no dark clumps).
Wet mix. Add milk, oil (or melted butter), and vanilla. Stir until you get a smooth batter. Scrape the bottom corners—dry pockets hide there.
Peanut butter swirl. Drop the peanut butter in dollops over the batter. Use the tip of a knife or toothpick to swirl it down and around. Don’t overmix; you want peanut streaks.
Chocolate chips. Sprinkle them on top or stir lightly in. They’ll melt into mini lava pools.
Microwave. Cook on HIGH 60 seconds. Check. The top should look mostly set but slightly glossy in the center. If still very wet, microwave in 10‑ to 15‑second bursts until just set around the edges but soft in the middle. Total time is usually 70–90 seconds depending on microwave wattage.
Rest. Let the mug sit 1 minute to finish steaming. The crumb sets up and hot spots calm down. Yes, waiting is annoying. Do it anyway.
Finish & eat. Top with an extra peanut butter drizzle, a pinch of flaky salt, or a scoop of ice cream if you’re living right. Eat straight from the mug.

Common Mistakes to Avoid

Using a tiny mug. Batter overflow in the microwave is a horror show. Use a big mug with high sides.
Overcooking. Mug cakes turn rubbery fast. Stop when the top is just set; the carryover heat finishes the middle.
Skipping the mix scrape. Dry flour bombs at the bottom ruin the bite. Scrape those corners!
Using dry natural peanut butter straight from the fridge. It clumps. Warm or stir it first so it swirls.
Nuking without pause. Microwaves vary. Start at 60 seconds, then finish in short bursts. Cake forgiveness is limited.
Going low on sugar without balancing fat/liquid. Sugar helps moisture and tenderness. If you cut it, add a teaspoon extra milk or a drizzle of syrup.

Alternatives & Substitutions

Gluten‑free: Use a 1:1 gluten‑free baking blend. Add a teaspoon extra milk if batter seems thick.
No peanut butter? Use almond butter, tahini (surprisingly awesome with chocolate), or sunflower seed butter if nut‑free.
Lower sugar: Use 1 tbsp sugar + 1 tbsp mashed banana or applesauce; texture gets slightly moister.
Protein mug cake: Swap 1 tbsp flour for chocolate or vanilla protein powder; add 1 tsp extra milk.
Vegan: Use plant milk + oil (not butter) + dairy‑free chocolate chips. Works great.
Lava version: Push 1 square dark chocolate or a mini peanut butter cup into the center before microwaving.
Extra fudgy: Add 1 tsp brewed coffee or 1 tsp yogurt/sour cream to the batter. Richer texture.
Airy cake vibe: Separate 1 egg, whisk white lightly, fold in (halve other liquids). Only if you want to fuss a little.

IMO, the peanut butter cup center + flaky salt finish is peak late‑night dessert.

FAQ (Frequently Asked Questions)

Can I make this without cocoa powder?
Yes. Skip cocoa, add 1 extra tbsp flour, and you’ll have a vanilla peanut butter mug cake. Toss in chocolate chips to compensate.
Natural or regular peanut butter?
Both work, but natural (just peanuts + salt) is thicker and may sink. Stir well and warm 5 seconds before swirling. Regular creamy gives smoother pockets.
Can I bake it in the oven?
Totally. Use an oven‑safe ramekin. Bake at 350°F (180°C) for about 12–15 minutes until just set on top.
Why did my mug cake turn rubbery?
Likely overcooked or too much flour. Spoon flour into the tablespoon and level it—don’t pack. Stop microwaving when slightly underdone.
Can I double the recipe?
Yes, but divide into 2 mugs. Doubling in one mug leads to uneven cooking (dry top, raw core).
Can I make it oil‑free?
You can sub 1 tbsp applesauce or mashed banana for the oil, but the cake will be more spongy and less rich.
How do I store leftovers?
Leftovers? Cute. If it happens, cover and chill up to 1 day. Reheat gently 10–15 seconds; texture will be drier, so add a splash of milk or ice cream.

Troubleshooting Microwave Times (Quick Guide)

700W microwave: Start 75 seconds, then 10‑second bursts.
1000W microwave: Start 60 seconds; usually needs +10–15 seconds.
1200W+ microwave: Start 50 seconds; check early to prevent rubber cake.

If the cake pulls away from the sides, you went too far. Still edible—just add ice cream and pretend it’s a brownie.

Quick Nutrition Snapshot (estimate, varies by ingredients)

1 mug (with oil, sugar, PB, milk, chips): about 500–550 calories; 9–12 g protein; 30–35 g fat; 50–55 g carbs. Swap low‑fat milk, less sugar, and no chips to cut it down fast.

Final Thoughts

Chocolate peanut butter mug cake exists for the exact moment when your sweet tooth clocks in and your patience clocks out. It’s fast, warm, gooey, and totally customizable—even if your pantry looks like a snack aisle after finals week. Now go impress someone (or just yourself) with a hot, melty, microwave miracle in a mug. You’ve earned dessert.