Once the fudge has thickened, remove it from the heat. From this point on, work as quickly as possible, because the mixture will harden pretty quickly. Add the white chocolate and whisk until all the chocolate has melted.
Transfer the fudge mixture into prepared pan. Allow the fudge to cool slightly at room temperature, then cover the pan and leave it to set in the fridge for at least 4 hours. Once the fudge has set, cut it up in pieces (I recommend small pieces because the fudge is very rich) and serve.
Fudge will keep in the fridge for up to 2 weeks. Serve it cold or at room temperature (my preference).
Recipe adapted from What Jessica Baked Next