Learn how to turn a regular box of cake mix into a super quick and satisfying treat in your microwave in under 10 minutes!

The best trick for this easy treat is swapping the butter or oil out for an overly ripe banana. The result is an incredibly moist cake, with a semi-healthier twist!  

Negative Calorie Chocolate Cake

Cooking cake in the microwave is a skill everyone should know. More-so, cooking a cake in the microwave from a boxed cake mix is the ultimate talent. We know we’re not the only ones who get a nagging sweet tooth late at night.

One night a box of Betty Crocker Cake Mix was staring at me from my pantry just begging to be baked up, but I didn’t have the patience to wait 40 minutes for it to cook and I didn’t want to heat up the already warm house with my oven. Thus, this Secret Ingredient Microwave Chocolate Cake being born! 

Negative Calorie Chocolate Cake

Why This Microwaved Chocolate Mug Cake Recipe Works 

  • It is the quickest and easiest way to make a cake knocking your cooking time from 40 minutes to under 10 minutes. 
  • It is a perfect serving size for one person per ramekin, or you have the ability to bake the cake in one go in a microwave safe cake pan! 
  • Experimenting has led to some delicious additions, toppings, and fillings. 
  • Clean up is fast with just a fork and a mug and take only 1 minute to bake up! 
  • Overly ripe bananas easily replace butter and oil in this recipe leaving you with a delicious and moist cake.   

ingredients for microwave chocolate mug cake.
Ingredients For Microwaved Chocolate Cake    

  • Betty Crocker Super Moist Chocolate Cake Mix *secret ingredient* 
  • Overly ripe banana 
  • Eggs 
  • Water 
  • Non-stick cooking spray 

How to Cook Secret Ingredient Chocolate Cake in the Microwave

  1. In large bowl, mixed together the smashed banana, eggs, and water. Whisk until combined.

  2. Stir in cake mix – stir vigorously for a couple of minutes until well mixed.

  3. Spray ramekins with cooking spray. Pour batter into ramekins up to 2/3 full.

  4. Microwave depending on the amount of ramekins and wattage of your microwave. Check the FAQs for best cooking times! 

  5. Check with toothpick to see if cake is done.  Mushy cake mix stuck to toothpick? Add another 30 seconds.  Cake crumbs on toothpick? Done! 

In case you don’t have ramekins, pour batter into a 9×11 glass microwave safe baking dish. Pour until the batter reachers just half way up the sides. Microwave for 11 minutes on medium-high, then check for doneness with a toothpick or cake tester. Once baked, cut into squares! 

Negative Calorie Chocolate Cake


How long to microwave my cake? 

The timing of your cake will vary on the strength and wattage of your microwave. Here is a general rule for microwave cooking time:
-Two Ramekins: Microwave on medium-high for 5 minutes 
-Three-Four Ramekins: Microwave on medium-high for 6 minutes
– Five-Six Ramekins: Microwave on medium-high for 7 minutes

How can I quickly Ripen a Banana in the Microwave? 

Microwaving a banana will turn it brown, converting the starch into sugar. This allows the banana to become a little sweeter, but the best result is how soft it becomes, making it the perfect addition to this microwave chocolate cake! 

Quickly ripen a banana in the microwave by poking the peel with the tip of a knife. Then, wrap the banana in a paper towel and microwave for 30 seconds at low heat.

How Can I Elevate my Cake?   

A few of our favorite ways to elevate a simple, but delicious cake are:
-Drop a big chunk of chocolate in the middle of batter in each ramekin resulting in a molten chocolate cake. 
-Toss fresh raspberries into the better for a super fresh element.
– Top your moist chocolate microwave cake with whipped cream or ice cream! 

Negative Calorie Chocolate Cake

I always make this with Betty Crocker Super Moist Cake Mix Dark Chocolate (the one with a Hershey's logo on it). I'm sure it will taste just as good with other brands of cake mix, but this is my preference. The ingredients below are based on the back of the box (with the exception of the banana) If you use a different brand of cake mix, follow their instructions for ingredients, replacing the banana for the oil or butter. Of course, if you aren't on a diet - ditch the banana idea and just use the oil/butter as the recipe calls for.
2 from 22 votes
Prep Time 5 minutes
Cook Time 6 minutes
Total Time 11 minutes
Course Dessert
Cuisine American
Servings 6 people


  • 1 box Betty Crocker SuperMoist Cake Mix Dark Chocolate
  • 1 very ripe banana smushed well with a fork
  • 3 eggs
  • 1 1/3 cups water
  • Cooking spray to spray the ramekins


  • In large bowl, mixed together the smushed banana, eggs and water. Whisk until combined.
  • Stir in cake mix - stir vigorously for a couple of minutes until well mixed.
  • Spray ramekins with cooking spray. Pour batter into ramekins up to 2/3 full.
  • Every microwave is different - here are some guidelines:
  • -For 2 ramekins: microwave on MEDIUM-HIGH (I set my microwave on power strength 8 ) for 5 minutes
    -For 3-4 ramekins: 6 minutes
    -For 5-6 ramekins: 7 minutes
  • Check with toothpick to see if cake is done. Mushy cake mix stuck to toothpick? Add another 30 seconds. Cake crumbs on toothpick? Done.
  • Top with warm chocolate sauce, reduced pomegranate juice, fresh raspberries or a sprinkling of powdered sugar (or all of the above!)


Note on the banana: It should be a super-ripe brownish banana...like in the photo above. If you don't have a super ripe banana, quickly ripen your banana in the microwave! *Read full blog post for the full how to!  
Note on the microwave times: Each microwave is different. Use the times listed in the recipe and test with a toothpick. Just note your final time so that you won't have to check for doneness next time! 
You'll need about 4-6 small, individual serving sized ramekins.
Keyword Cake, chocolate cake, Easy Recipe, microwave, Microwave Recipes, Mug Cake
Tried this recipe?Let us know how it was!