I too have a similar problem to a fellow poster … I love the Nigella Brownies featured in HOW TO BE A DOMESTIC GODDESS....but I can’t seem to get the consistency right. I have lowered the temperature as suggested for my fan oven but I still have the same problem - inconsistent ‘set’. I realise they are supposed to be squidgy in the centre but when I bake them the centre is always too runny and if I cook longer then the outside edges go dry. Any advice?
Nigella's Brownies (from HOW TO BE A DOMESTIC GODDESS) should be fairly squidgy and soft when cool. To check if they are done insert a cake tester into the centre - it should come out with damp crumbs attached, rather than raw brownie batter. Although normally we suggest reducing the temperature of a fan oven by 20°C, fan ovens can still cook more quickly and it may help to reduce the oven by a further 20°C (to 140°C fan) to get a more even bake, even if it takes a little longer.
Try to use a pan as close to the specified dimensions as possible as a smaller, deeper pan could cause the outside of the brownies to cook but leave the inside undercooked. As brownies don't rise much, it may also help to rotate the pan by 180 degrees halfway though the cooking time, particularly if the batter in the corners is too well-cooked. Hot and cool spots should not be an issue in a fan oven, but it may help if the air circulation isn't completely even. Also, if you are using a dark-sided pan the brownies can cook more quickly as dark surfaces absorb heat more quickly. Reducing the oven temperature a little more can help to offset this, or switch to a pan made from lighter-coloured or shiny material. We prefer to avoid baking brownies in heatproof glass dishes as the glass retains heat when it comes out of the oven, which can cause the brownies to continue cooking once they come out of the oven and become too cake-like.