I've been asked to make a mint-flavoured version of the 'birthday cake' brownie recipe in Domestic Goddess. In search of ideas for added crunch, I'm considering using those brown sugar crystals you can buy to use in coffee. Would they simply melt during the cooking process or would they behave in a similar way to chocolate chips and retain their shape and crunch?
Nigella's recipe for Brownies (from HOW TO BE A DOMESTIC GODDESS) are a good alternative to a traditional birthday cake and can look fabulous if piled high and spiked with cake candles. A mint flavoured version could be made, though we would probably avoid adding mint flavouring to the batter and instead look for minty add-ins such as chocolate coated mint fondants (such as Peppermint Patties or Bittermints) instead of the walnuts.
Sugar with larger crystals, such as Demerera (turbinado) sugar and sanding sugars, usually keep some of their crunch when baked, so it is best to use them as a topping for cakes, cookies and muffins as they will tend to dissolve more quickly if mixed into a cake batter. Large coffee sugar crystals (in the UK called amber sugar crystals) could be used as a topping, though they are not as refined as white sugar and have a slightly caramelly flavour which may not quite complement the mint in the brownie. We would suggest maybe using a white sugar with large crystals, such as sanding sugar or pearled sugar. This sugar could be flavoured with mint, either using fresh mint leaves or a good-quality extract, and then scattered over the top of the brownie batter before baking. Please note however that the sugar will not retain its crunch for that long, so we would suggest making the brownies no more than a day ahead. The sugar will soften more quickly if the brownies are stored in an airtight container or if the weather is humid.