Chocolate Topping Turning White

Our answer

Millionaire's Shortbread (from Domestic Goddess) has a topping made from melted chocolate that is then left to set before cutting into bars. Ideally the Millionaire's Shortbread should be left to set in a cool place rather than the fridge. We suspect that the white spots appearing on the chocolate of your bars is something known as "bloom.

Bloom happens on chocolate when the chocolate goes through several uncontrolled changes of temperature. Chocolate is a fairly delicate mix of cocoa solids, cocoa butter and sugar (plus emulsifiers and sometimes other fats). When chocolate is made it is heated and cooled to very specific temperatures to keep the mixture shiny and emuslified. However if the temperature changes are large, and possibly frequent, then the cocoa butter can separate out from the chocolate. The butter then appears as a white film or white spots on the chocolate. We suspect your bars may be being cooled or kept in the fridge and this will increase the chances of bloom forming. If possible let the bars set and store them in a cool place but out of the fridge. Chocolate with bloom on is still fine to eat, it just doesn't look quite as nice.