Fixing an egg custard should start with preventative measures ... Then, you can follow the temperature and cooking times specified in your recipe. If you make individual ramekins like this recipe for ...
Bake the tarts in the oven for about 25 minutes - you may need to turn the temperature down to 180C/350F/Gas 4 for the final 10 minutes. You are looking for a very slight dome on the custard ...