This recipe was first published here on 30th June 2020 and has been updated with new information and images.

This gooey chocolate mug cake is gooey from chocolate chips and marshmallow with a perfectly moist, fluffy cake. It’s dangerously addictive and even more dangerously easy.

  • So quick and easy to make
  • Takes 5 minutes start to finish!
  • Moist, fluffy and gooey all at once
  • You just need a mug, ingredients and a fork
  • Single serve but the recipe is scalable

It couldn’t be easier and this gooey chocolate cake in a mug will cure your chocolate cravings and there’s barely any washing up!

This is one of those desserts you make when you want something more than candy but can’t be bothered baking. It’s so quick and being an individual serve means you don’t need to worry about leftovers.

You’ll definitely love these fudgy marshmallow brownies too or try this Biscoff mug cake.

Marshmallow topped chocolate mug cake on a saucer.

Table of contents

Truly the best fluffy mug cake

Microwave mug cake recipes can be hit and miss. Some are over-simplified and the flavour just isn’t there. Others end up with a chewy or rubbery texture or are dry and just not at all appetising.

Not this one. This mug cake is a real treat. It’s rich in chocolate flavour, has a soft, fluffy texture and is incredibly moist. It’s also super easy to make. So easy, in fact, you can make it right in the mug if you like and save further washing up.

While some call for egg, this is an eggless mug cake and you can even swap the milk for a non-dairy variety making it perfect if you have dietary restrictions or preferences.

Top down view of the top of a gooey chocolate mug cake.

Ingredients you’ll need

Detailed quantities and instructions in the recipe card below.

  • Milk: I use whole milk but you can use light or even an milk alternative like coconut milk, almond milk, oat milk or soy milk.
  • Oil: Vegetable oil or even a light flavoured extra virgin olive oil, give this chocolate mug cake it’s beautiful moist texture.
  • Brown sugar: Brown sugar here adds flavour as well as sweetness and also adds to the moisture content.
  • Flour: I use regular plain flour (all-purpose flour) here.
  • Cocoa powder: I used dutch processed cocoa powder for it’s dark colour and smooth flavour but regular unsweetened cocoa powder will work.
  • Baking powder: Just a little baking powder gives it a fluffy texture.
  • Chocolate chips: I use dark chocolate chips here (or semi-sweet). You can very easily use milk chocolate chips, white chocolate chips or even peanut butter chips.
  • Marshmallows: I love those big campfire marshmallows for this but any you have on hand will work.
  • Cookies / biscuits: I use digestive cookies or graham crackers (when I can get them). Even Arnotts malt-o-milk are great.

Those last 3 ingredients are what take this from a gooey chocolate mug cake to a s’mores mug cake and are worth every moment.

Feel free to leave out the cookies and marshmallow for a simplified gooey chocolate mug cake.

How to make mug cake

A collage showing how to make chocolate mug cake.

Detailed quantities and instructions in the recipe card below.

  1. Mix together wet ingredients and sugar so they’re full combined.
  2. Add the dry ingredients – flour, cocoa, baking powder, salt and chocolate chips. Mix with a spoon until just combined.
  3. Add a marshmallow, cookies and more chocolate chips.
  4. Cook for 70 seconds (varies depending on your microwave)

How long to cook mug cake

The length of cooking time required to cook your mug cake will depend on the power of your microwave and how many you’re cooking at once. In my microwave (1000W), this mug cake takes exactly 70 seconds every time for a single mug on high. A little longer for 2 or more.

It’s important to test with your microwave. If it’s particularly powerful, start at 40-45 seconds or a lower wattage microwave might take up to 2 minutes. Test until you know how yours works, then write it down so you always know how long you need to cook your mug cake to perfection.

Tips for making perfect chocolate mug cake

  • Make sure your mug is microwave safe – some get very hot in the microwave and don’t use any that have metallic features or decorations.
  • Use a fork and scrape right around into the corners of the mug when mixing so everything is combined.
  • All microwaves vary – mine is 1000W and it takes exactly 70 seconds on high for 1 mug cake
  • Cooking more than one at a time will require a longer cooking time.
  • If doing a batch, It will be quicker to mix it in a bowl first, then divide into cups.
A spoonful of chocolate mug cake being scooped out of a mug.

Variations and substitutions

  • Milk – I found regular dairy full fat milk to give the best flavour but you can swap it for reduced fat milk or even non-dairy milks if you prefer.
  • Dark brown sugar – swap it for light brown sugar or even white sugar. You can also use monk fruit sweetener for a lower calorie version
  • Filling: Add a dollop of Nutella or peanut butter to the middle of your mug cake to give it an extra gooey centre.
  • Chocolate sauce: Drizzle over some chocolate fudge sauce to serve for added indulgence.
  • Caramel sauce: Or top it with this amazing homemade caramel sauce.
Chocolate mug cake with marshmallows on a saucer.

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Top down view of the top of a gooey chocolate mug cake.

S’mores Gooey Chocolate Mug Cake

Yield: 1 mug cake
Prep Time: 5 minutes
Cook Time: 2 minutes
0 minutes
Total Time: 7 minutes
4.9 from 24 ratings
A rich, satisfying chocolate cake in just 5 minutes? You can do it, with this S’mores Gooey Chocolate Mug Cake recipe. This eggless mug cake, topped with gooey toasted marshmallow is so easy, it can be made right in the mug. 
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Video

Ingredients

  • 2 ½ tablespoons milk (full fat) (notes) (50ml)
  • 1 ½ tablespoons vegetable oil (notes) (30ml)
  • 2 tablespoons dark brown sugar (notes)
  • 3 tablespoons flour (notes)
  • 3 teaspoons dutch processed cocoa (notes)
  • ¼ teaspoon baking powder
  • pinch of salt
  • 1 heaped teaspoon chocolate chips
  • ½ large marshmallow
  • ½ cookie (graham / digestive), crumbled

For best results, always weigh ingredients where a weight is provided

Equipment

Instructions
 

  • Add the milk, oil and sugar to a microwave safe mug and stir well with a fork. A large mug like a builders mug (12oz / 1 ½ cup capacity) works perfectly.
  • Add the flour, cocoa, baking powder, salt and most of the chocolate chips and mix until the batter is well combined.
  • Drop the half a marshmallow on top, then scatter over crumbled cookies and the remaining chocolate chips.
  • Cook on high for 70 seconds (see notes as all microwaves vary), then let it sit for a minute.
  • Optional: Toast the marshmallow with a kitchen blow torch.
  • Take it to another level by adding a scoop of vanilla ice cream and some raspberries to the top.
  • Please take a moment to leave a comment and rating. It's appreciated and so helpful.

Notes

  1. I use a standard Australian tablespoon which is 20ml or equal to 4 teaspoons worldwide.
  2. Cocoa – I like dutch processed cocoa for it’s dark colour and smooth flavour but regular unsweetened cocoa will work fine.
  3. Make sure your mug is microwave safe – some get very hot in the microwave
  4. All microwaves vary – mine is 1000W and it takes exactly 70 seconds on high for 1 mug cake
  5. Cooking more than one at a time will require a longer cooking time.
For more cakes and cupcakes, click here.
Calories: 603kcal
Author: Marie Roffey
Course: Dessert, Sweets
Cuisine: American, Australian, World
Have you tried this recipe?Don’t forget to leave a rating and comment below and let me know how it was! I love hearing from you. Nutrition information is approximate and derived from an online calculator. The brands you use may cause variations.