Cheese Fondue problems, diagnosed

First decide whether the fondue is truly broken or simply too thin. A smooth, glossy fondue that is uniformly runny can often be corrected with more cheese added gradually or with a small starch slurry. A fondue with rubbery or stringy cheese sitting in greasy or watery liquid has broken: take it off direct heat. More cheese or more cooking can make that branch worse. Nigella distinguishes hard-lumpy fondue from greasy split fondue, while an ACS Omega study shows that starch is a genuine stabilizer against irreversible phase separation.