How to Melt Marshmallows Without Ruining Them

Marshmallows melt badly if you rush them. They go stringy, then grainy, then they seize into a lump that will not come back. All three failures have the same cause, and avoiding it is mostly a matter of patience and a splash of liquid.

Why they seize

A marshmallow is concentrated sugar syrup, gelatine and air. When you heat it, three things happen at different rates: the gelatine melts at close to body temperature, the air escapes, and the sugar continues to concentrate as water evaporates.

Push the heat too hard and the sugar concentrates faster than the mixture can stay fluid. The sugar recrystallises, and once it has crystallised you cannot un-crystallise it. That is the grainy texture. Keep going and the gelatine begins to break down, which is the stringy stage, and then you have a lump.

What marshmallows are and why they behave this way is covered in what are marshmallows made of.

The method that works

1. Add liquid. A tablespoon of water, milk or cream per 100g of marshmallows. This is the single biggest difference between a smooth melt and a seized one, because it keeps the sugar below the concentration at which it recrystallises.
2. Add a little fat if you want it glossy. A knob of butter per 100g gives a sauce that stays pourable as it cools.
3. Low heat, and stir constantly. A heavy pan on the lowest setting, or a bowl over barely simmering water. The water in the pan below should not touch the bowl.
4. Take it off before it looks finished. Residual heat will melt the last few pieces. Stirring off the heat is safer than holding it on.

In a microwave

It works, and it is the easiest way to overshoot. Short bursts of 10–15 seconds at medium power, stirring between every one. Marshmallows puff up dramatically before they melt, so use a bowl three times bigger than you think you need. When they have roughly doubled and the edges look wet, stop and stir — they will finish in the residual heat.

If it goes grainy, it has gone too far and no amount of stirring will recover it.

Melting them into chocolate

Do the two separately and combine off the heat. Chocolate and marshmallow want different temperatures, and melting them together generally overheats one to rescue the other. Melt the chocolate gently, melt the marshmallows with a splash of liquid, then fold.

If the chocolate has gone dull or streaky before you started, that is bloom rather than spoilage — why chocolate turns white explains what happened and whether it still tastes right.

Which marshmallows melt best

Gelatine-set marshmallows melt most predictably, because gelatine liquefies at a low temperature and gives a smooth result. Egg-white and plant-set marshmallows — the vegetarian and vegan versions — behave differently: they tend to hold their shape longer, foam more, and are more prone to going grainy. They can be melted, but go slower and add slightly more liquid.

Size matters more than people expect. Small marshmallows melt far more evenly than large ones, because the outside of a large one is well past its ideal temperature before the middle has softened. If you have a choice, use the small ones.

Toasting rather than melting

Different job, opposite technique. Toasting is about caramelising the outside fast while the inside softens — high heat, close to the flame, turned constantly, and eaten immediately. The molten middle is the gelatine doing exactly what it does in a pan, just faster and in a smaller volume.

Browse the range: marshmallows. For bigger quantities, bulk and trade carries the same lines by the kilo.