Microwave Chocolate Peanut Butter Lava Mug Cake

Quick Recipe Version (TL;DR)

• Yield: 1 mug cake (1 generous serving)
• Prep Time: 5 minutes
• Cook Time: 1 minute 20 seconds
• Total Time: 7 minutes (includes 1 minute rest time)

Quick Ingredients

• 4 tbsp (32 g) all-purpose flour
• 2 tbsp (12 g) unsweetened cocoa powder
• 3 tbsp (38 g) granulated sugar
• 1/4 tsp baking powder
• 1/8 tsp fine salt
• 3 tbsp (45 ml) whole milk
• 2 tbsp (30 ml) neutral oil (canola or vegetable)
• 1/4 tsp vanilla extract
• 1 tbsp (16 g) creamy peanut butter
• 1 tbsp (14 g) semisweet chocolate chips
• 1 pinch flaky sea salt

Do This

• 1) In a 12–16 oz (355–475 ml) microwave-safe mug, mix flour, cocoa, sugar, baking powder, and fine salt.
• 2) Stir in milk, oil, and vanilla until smooth and glossy.
• 3) Spoon peanut butter into the center; gently nudge it down slightly.
• 4) Cover peanut butter with a little batter; sprinkle chocolate chips on top.
• 5) Microwave on HIGH for 1 minute 20 seconds.
• 6) Rest 1 minute, then finish with a pinch of flaky salt and eat warm.

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Why You’ll Love This Recipe

• True lava center: Peanut butter stays gooey and rich in the middle.
• Big chocolate flavor: Cocoa-forward, fudgy texture with melty chocolate chips on top.
• Fast and minimal dishes: Mix right in the mug; dessert is ready in minutes.
• Sweet-salty perfection: A pinch of flaky salt makes the chocolate and peanut butter pop.

Grocery List

• Produce: Optional: fresh raspberries or sliced strawberries (for serving)
• Dairy: Whole milk
• Pantry: All-purpose flour, unsweetened cocoa powder, granulated sugar, baking powder, fine salt, neutral oil (canola or vegetable), vanilla extract, creamy peanut butter, semisweet chocolate chips, flaky sea salt

Full Ingredients

For the chocolate mug cake batter

• 4 tbsp (32 g) all-purpose flour
• 2 tbsp (12 g) unsweetened cocoa powder
• 3 tbsp (38 g) granulated sugar
• 1/4 tsp baking powder
• 1/8 tsp fine salt
• 3 tbsp (45 ml) whole milk
• 2 tbsp (30 ml) neutral oil (canola or vegetable)
• 1/4 tsp vanilla extract

For the peanut butter lava center

• 1 tbsp (16 g) creamy peanut butter

For topping and finishing

• 1 tbsp (14 g) semisweet chocolate chips
• 1 pinch flaky sea salt
• Optional for serving: 1 small scoop (about 1/4 cup / 60 ml) vanilla ice cream

Step-by-Step Instructions

Step 1: Choose the right mug

Use a 12–16 oz (355–475 ml) microwave-safe mug. This size helps prevent overflow and gives the cake room to rise slightly. If your mug is smaller than 12 oz, divide the batter between two mugs and microwave them separately for the same time.

Step 2: Mix the dry ingredients in the mug

Add the flour, cocoa powder, sugar, baking powder, and fine salt directly into the mug. Stir well with a fork until the cocoa looks evenly distributed and there are no obvious streaks. Mixing thoroughly here helps prevent bitter cocoa pockets later.

Step 3: Stir in the wet ingredients until smooth

Add the milk, neutral oil, and vanilla extract. Stir until you have a smooth, glossy batter with no dry flour hiding at the bottom. Scrape the sides and bottom of the mug with your fork as you mix so everything is fully combined.

Step 4: Add the peanut butter center and top with chocolate chips

Spoon the peanut butter into the center of the batter. Use the tip of your spoon to nudge it down slightly so it’s surrounded by batter (this helps it become a gooey “lava” pocket rather than drying out on top).

If the peanut butter is sitting on the surface, spoon a small amount of batter over it to lightly cover. Sprinkle the chocolate chips evenly over the top.

Step 5: Microwave precisely

Microwave on HIGH for 1 minute 20 seconds. The cake should look set around the edges and slightly glossy on top, with the center still soft. The mug will be hot; carefully remove it using a towel or oven mitt.

Step 6: Rest, finish with flaky salt, and serve warm

Let the mug cake rest on the counter for 1 minute. This short rest finishes the carryover cooking and thickens the center so the peanut butter stays lava-like instead of runny.

Sprinkle a pinch of flaky sea salt over the top. Eat straight from the mug while warm, or add a small scoop of vanilla ice cream for extra contrast.

Pro Tips

• Microwaves vary: If your cake looks underdone after 1 minute 20 seconds, microwave only in 10-second bursts to avoid overcooking. Lava cakes turn from fudgy to dry quickly.
• Mix thoroughly, but don’t overwork: Stir until smooth and no dry flour remains; then stop. Overmixing can make the texture a bit tougher.
• Center placement matters: Peanut butter in the middle (and slightly submerged) gives the best molten core.
• Use creamy peanut butter for the gooey effect: Natural peanut butter can separate and bake up a little drier unless it’s very well stirred.
• Flaky salt is not optional if you love contrast: A tiny pinch makes the chocolate taste deeper and the peanut butter taste more “peanutty.”

Variations

• Reese’s-style center: Replace the peanut butter with 1 tbsp (18 g) peanut butter chips or a mini peanut butter cup pressed into the center.
• Extra-dark chocolate: Use dark chocolate chips and add 1/8 tsp instant espresso powder to the dry ingredients for a deeper cocoa flavor.
• PB&J lava: Add 1 tsp (7 g) strawberry or raspberry jam on top of the peanut butter before covering with a little batter.

Storage & Make-Ahead

This mug cake is best eaten fresh while warm and gooey. If needed, cover and refrigerate for up to 1 day. Reheat in the microwave on HIGH for 15 seconds to soften the center again (it won’t be quite as lava-like as the first cook). You can pre-measure the dry ingredients into the mug earlier in the day; when you want dessert, stir in the wet ingredients, add peanut butter, and microwave.

Nutrition (per serving)

Approximate, for 1 mug cake: 560 calories; 26 g fat; 78 g carbohydrates; 9 g protein; 46 g sugar; 5 g fiber; 520 mg sodium.