It's 9pm on a Tuesday. The kitchen's clean, the dishwasher's already running, and you want something sweet badly enough to be standing in front of the pantry doing sums.
Turning on the oven for one person is absurd. 12 minutes to preheat, a tin to grease, and then a cake sitting on the bench that you'll be eating for four days.
So here's the other option. A cup, a fork, 90 seconds in the microwave, and a warm chocolate cake that fits in one hand.
We make silicone drinkware. Which means we spend a lot of time telling people what our cups can do. This one surprises people, so we're going to explain exactly how it works, exactly where the limit sits, and what happens if you push past it.
The base recipe
This is sized for a 300ml cup, which is what the Bubble Gin Cup holds. It comes out to roughly 110ml of batter, a bit over a third of the way up. If you're using something bigger, you can scale it up. If you're using something smaller, don't, because the batter roughly doubles as it cooks and you'll be cleaning the microwave.
You need:
- 4 tablespoons self-raising flour (about 30g)
- 2 tablespoons caster sugar
- 1½ tablespoons cocoa powder
- A pinch of salt
- 3 tablespoons milk
- 2 tablespoons neutral oil
- A splash of vanilla
What to do:
- Put the dry ingredients in the cup and stir them with a fork until the cocoa disappears. Do this properly. Pockets of raw baking powder taste like soap and you'll find them.
- Add the milk, oil and vanilla. Stir until it comes together and then stop. A few lumps are fine.
- Microwave at 50% power for 60 seconds.
- Check it. The top should look set but still a bit tacky. If it's wet, go again in 10-second bursts.
- Rest it for a minute before eating. It keeps cooking in the cup.
Why most mug cakes are terrible
You've probably had a bad one. Dense, chewy, faintly rubbery, with a dry crust and a raw patch in the middle. There are four reasons, and all of them are fixable.
You cooked it too long.
This is nearly always the problem. In a microwave, the difference between a soft cake and a bouncy one is fifteen seconds.
Microwaves heat the water in the batter, and once that water has boiled off, the temperature keeps climbing and the starch goes hard. Undercook it slightly and let residual heat finish the job.
You used full power.
America's Test Kitchen developed their mug cake at 50% microwave power for exactly this reason, because the gentler heat kept the crumb tender.
Full power cooks the outside fast and leaves the centre behind. Half power for longer beats full power for less, every time.
You added an egg.
Egg protein sets hard and fast under microwave heat with nothing to slow it down. In an oven, a cake has fifteen minutes for the structure to develop gradually.
In a microwave it has ninety seconds, and egg turns that into something closer to a sweet omelette. Skip it. The self-raising flour and the oil do the work.
You overmixed.
Stirring develops gluten. In a full-sized cake that's balanced out by the long bake. Here, it goes straight to chewy. Stir until combined and walk away.
The cup is doing more than holding the batter
Ceramic mugs absorb microwave energy. That's why the mug is often hotter than the cake and why you burn your fingers getting it out.
Silicone barely absorbs microwaves at all. The energy goes into the batter, the cup stays cool enough to pick up, and the heating is more even because you're not fighting a hot ceramic wall cooking the edges from the outside.
There's a second thing, which is that silicone flexes. A mug cake in a ceramic mug has to be eaten out of the mug, or dug out with a spoon in pieces.
Squeeze the sides of a silicone cup and the whole cake lifts out clean onto a plate. If you're serving these to people, that's the difference between dessert and a snack you ate standing up.
The trade-off, and there's always one: silicone doesn't brown food. There's no Maillard crust, no crisp edge.
What you get is a soft steamed pudding texture. It's genuinely lovely, and it isn't the same thing as a baked cake. If you were expecting a crackly top, you'll be disappointed by physics rather than by the recipe.
Is silicone actually safe to heat food in?
Fair question, and the honest answer has a number in it.
In 2025, researchers testing silicone bakeware found that new moulds heated to 177°C for an hour transferred measurable cyclic siloxanes into a fatty food simulant, roughly 105 micrograms per gram, and released them into the air as well.
Emissions dropped by about 95% after three uses, and the study's practical suggestion was to heat new silicone bakeware a few times before cooking with it.
A mug cake is ninety seconds, near 100°C, in a batter that's mostly milk and flour. Migration from silicone rises with temperature, time and fat content, and the microwave scenario is at the bottom of all three scales. The oven scenario is at the top.
Which is why the boundary at the start of this article isn't a legal disclaimer. Temperature is the variable that matters, and staying under it is the entire safety story.
Beyond that: food-grade silicone is made from silica, which comes from sand, rather than crude oil. It contains no BPA, BPS or phthalates.
Every STYLD.® piece is premium food-safe silicone, FDA and CPSIA approved. Cheap filler-heavy silicone from an unnamed supplier is a different product wearing the same word, which is the reason we're specific about ours.
Five more things worth making in a cup
Once you stop thinking of it as drinkware, the silicone cups start earning their cupboard space.
Overnight oats. Rolled oats, milk, yoghurt, whatever fruit is going soft. Lid it with a saucer, leave it in the fridge, eat it cold or warm it for 40 seconds. The flex makes it easy to get the last of it out.
A poached egg. Crack an egg into a cup with a tablespoon of water, cover it, microwave at 50% for around 50 seconds. Pierce the yolk first or it'll burst.
Melted chocolate. 20-second bursts at half power, stirring between. Silicone doesn't hold onto heat the way ceramic does, so the chocolate is less likely to seize while you're distracted.
Single-serve porridge. Half a cup of oats, a cup of milk, two minutes at half power. It won't boil over the way it does in a saucepan because you can watch the whole thing.
Anything from the freezer. These sit at -20°C without going brittle, so a cup of leftover soup or a stack of frozen berries goes freezer to microwave in one vessel. Fewer dishes, which is genuinely the point.
Frequently asked questions
Can you bake in silicone cups?
You can microwave in them, and a microwave mug cake works beautifully. You can't put drinking cups in a conventional oven, air fryer or grill.
Food-grade silicone drinkware is rated for everyday use between -20°C and 100°C, with material stability to around 140°C, while an oven runs at 180°C or higher. Silicone bakeware sold specifically for ovens is a different formulation with a different rating.
Why does my mug cake come out rubbery?
Almost always overcooking. Microwaves heat the water in the batter, and once that water boils off the temperature climbs fast and the starch and any egg protein set hard.
Cook at 50% power, stop while the top is still slightly tacky, and let it rest for a minute so residual heat finishes it. Adding an egg and overmixing both make it worse.
Is silicone safe to microwave?
Food-grade silicone is approved for food contact by the FDA and equivalent bodies, and it's chemically stable well past microwave temperatures.
Migration of silicone oligomers rises with heat, time and fat content, so a short microwave cycle in a moist batter sits at the low end of every risk factor. Extended high-heat oven use is the scenario the research focuses on.
Look for products that specify food-grade or platinum-cured silicone and state BPA, BPS and phthalate free.
Do you need egg in a mug cake?
No, and it's better without. Egg protein sets too quickly under microwave heat and produces a bouncy, omelette-like texture.
Self-raising flour provides the lift and oil keeps the crumb tender, so an eggless mug cake is softer and much harder to ruin.
What size cup do you need for a mug cake?
At least 250ml, and fill it no more than halfway. Mug cake batter roughly doubles as it cooks.
A 300ml cup with about 110ml of batter in it leaves plenty of headroom. Doubling a recipe into a single cup is the fastest way to clean a microwave.
Is silicone better than plastic for hot food?
Silicone is more heat stable than common food plastics like polypropylene, doesn't warp or go brittle with repeated heating, and doesn't contain BPA, BPS or phthalates.
It also won't shatter. The trade-offs are a higher price and no kerbside recycling, which means the case for it depends on keeping it for years.
How do you clean a silicone cup after baking in it?
Warm water and a normal wash, or the dishwasher. Silicone is non-porous so cake batter doesn't soak in. If oily residue leaves a slight film, a wash with hot water and a little bicarb soda clears it.
STYLD.® makes unbreakable silicone drinkware, designed in Australia for the way we actually live. Poolside, on the picnic rug, at the table, and occasionally at 9pm on a Tuesday. Reusable. Unbreakable. Made for every LifeSTYLD.
