I don’t have a regular built-in oven because Indian kitchens seldom do. I tried making the cake today at 150 degrees Celsius — the recommended temperature in the recipe for gas ovens — and my cake wasn’t cooked after 45 minutes. I left it longer and checked frequently for the next 20 minutes but it still was not baked in the centre.
Does this have to do with the oven temperature? Or the fact that the cake is on a plate rather than a rack as it would be in a normal oven? I baked the Apricot Cake With Cardamom and Rosewater before in my oven at the recommended setting for gas ovens and that came out fine.
Nigella's Ginger And Walnut Carrot Cake (from AT MY TABLE) is a single layer cake that is baked at in a normal oven 170c/325F. You should only use the 150c temperature if you are using a fan oven as the forced circulation of air around the cake makes it cook more quickly. The recipe itself does not have a recommended gas temperature though if it did it would be gas mark 3 (150c is only gas mark 2). It does sound to us as if the oven temperature is too low and should be closer to 170c, though if you have a convection microwave oven you may need to adjust the temperature if this is recommended in your handbook. Also not having the cake tin on a rack will make it more difficult to cook the centre of the cake as air can't circulate underneath the base of the tin. Opening and closing the door of the oven too often can also cause the cake to cook more slowly or sink, as the oven temperature will always drop when the door opens and can take time to rise again (this will also depend on what type of oven you have).
The Apricot Cake With Cardamom And Rosewater bakes at a higher temperature than the carrot cake, so it may have baked better as you were using a higher temperature and it could be worth trying the carrot cake again at a higher temperature.