I tried Nigella's Brownies recipe. While the top was as described in the recipe, the middle of the brownie just didn’t set. I checked at 22 minutes, 25 minutes, then covered the top with foil and gave it another 10 minutes. I then took it out and hoped it would set while it cooled but it didn’t. The middle was runny like chocolate sauce. I used a whisk to mix everything together. I didn’t whisk the eggs and sugar simply stirred it to incorporate the sugar. I did however add cranberries instead of walnuts as that’s all I had in the house. Please help!
Nigella's recipe for Brownies (from HOW TO BE A DOMESTIC GODDESS) should be slightly gooey in the centre once baked, though not liquid. You can use dried fruits instead of walnuts so we do not think that this is the reason for the brownies not setting. And not whisking shouldn't be the issue as long as all of the ingredients are thoroughly mixed. It is most likely that the problem is due to the oven temperature.
From the description it sounds as if the oven is a little too cool, which means that the brownies are not cooking completely in the centre. If you have an oven with electric elements on top and bottom then it may be worth checking that the bottom element is working efficiently. For a gas oven you may want to check the temperature with an oven thermometer as the internal thermostat may be old and starting to become less accurate. If you are using a smaller, deeper tin then this will also affect the baking time. Baking times can vary across different ovens, when you bake the brownies you should bake them until a cake tester comes out with damp crumbs attached but not liquid batter.