Why You’ll Love Molten Lava Chocolate Mug Cake Recipe

This mug cake is perfect when you’re craving something sweet but don’t want to pull out all the baking equipment. It uses melted chocolate and butter (rather than oil and cocoa powder alone) to deliver more depth of flavour and a truly “lava‑cake” style molten centre. It’s fast — from start to finish around five minutes — and easy to adapt for different tastes.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

2 tbsp butter
1 oz dark chocolate
3 tbsp milk
2 tbsp sugar
4 tbsp flour
1 tbsp cocoa powder
⅓ tsp baking powder
Pinch of salt
1‑2 plain chocolate truffles (for the molten lava core)

Directions

Choose a microwave‑safe mug of about 10–12 oz capacity.
In the mug, add the butter and the dark chocolate. Microwave in 15‑second increments until fully melted and combined.
Add the milk and stir to combine.
Add the sugar and stir in.
Sift in the dry ingredients (flour, cocoa powder, baking powder and salt) and stir, ensuring there are no streaks of flour and scraping down the sides and bottom of the mug.
Gently push 1‑2 plain chocolate truffles into the centre of the batter (no need to push all the way down).
Microwave on high for about 60–70 seconds, leaning toward the shorter time if unsure (you want the cake to be set on top but still gooey inside).
Allow to sit for a moment, then dust with powdered sugar if desired, and serve immediately.

Servings and timing

Yield: 1 mug cake
Total time: About 5 minutes (including prep and microwave time)

Variations

Use a milk or semi‑sweet chocolate truffle if you prefer a less intense dark chocolate lava centre.
Swap out plain dark chocolate for flavoured or filled chocolates (e.g., caramel‑filled) to change the molten core.
Use almond milk or oat milk instead of dairy milk to make it dairy‑free.
Try using coconut oil instead of butter for a different flavour profile.
Add a teaspoon of instant espresso powder with the cocoa for a mocha‑chocolate twist.
Stir in a handful of chopped nuts or chocolate chips into the batter for extra texture.

Storage/Reheating

Since this cake is best eaten immediately (to enjoy the molten centre), it’s not ideal for storing once cooked. If you have leftover batter, you could refrigerate it covered for up to 24 hours and microwave again when ready—however, the texture may be less ideal. To reheat a cooked mug cake, microwave for about 15‑20 seconds just to warm through, but note the molten core may firm up.

FAQs

How do I know when the mug cake is done?

You want the top of the cake to be mostly set but still slightly jiggly in the centre. Over‑cooking will lead to a dry, rubbery texture.

What size mug should I use?

A microwave‑safe mug around 10‑12 oz capacity is ideal. Too small and the batter may overflow or cook unevenly; too large and the rise may be minimal.

Can I use any kind of chocolate for the molten centre?

Yes—any plain (no nuts or wafers) chocolate truffle or chunk will work for the molten core. It will melt inside as long as the cooking time is correct.

Can I omit the cocoa powder or substitute it?

No—the cocoa powder is a key chocolate component of the batter and integral to the texture and flavour of this cake.

Can I reduce the sugar?

Yes—if you prefer a less sweet dessert, you can reduce the sugar from 2 tbsp down to about 1½ tbsp. Adjust to your taste.

Why are there lumps in my mug cake batter?

Lumps usually mean the dry ingredients weren’t sifted or incorporated fully. Make sure to sift the flour and cocoa, and stir thoroughly so there are no streaks of dry flour.

Why did my mug cake overflow or “explode”?

This can happen if the mug is too small, or if too much baking powder was used. Measure carefully and ensure the mug has enough capacity (10‑12 oz is recommended).

Why is my mug cake rubbery or dry?

Over‑cooking is the most common cause. With mug cakes you need to err on under‑cooking rather than over. Also ensure the measurements are accurate and you’re using the right kind of mug.

Can I bake this in a conventional oven instead of a microwave?

This recipe is designed specifically for microwave cooking, so using an oven would require adjusting time and temperatures significantly; the molten effect may not turn out the same.

Can I prepare the mixture ahead of time and cook later?

It’s not recommended—the batter tends to deflate and become denser if left before cooking. This will impact the rise and texture of your final cake.

Conclusion

If you’re looking for a simple yet indulgent dessert that satisfies a chocolate craving with minimal fuss, this molten lava chocolate mug cake is a great go‑to. With melted chocolate and butter, a gooey centre, and just a minute in the microwave, it’s perfect for a late‑night treat or a quick solo dessert. Enjoy!