Nigella suggests a tin foil baking tray of 30 x 20 x 5 cm. I used a 2 lb loaf tin with a paper liner. If not using a cake liner then line with Bake-O-Glide or baking parchment. Strangely you can get large and small 2lb tins. Mine is one of the larger ones. If yours is smaller and the cake mixture is looking as if it will reach the top of the liner as you are pouring it in then stop 2 cm before the top of the liner and make some muffins with the left over mixture.
In a saucepan melt 150 grams/21 oz butter, 300 grams/10.5 oz golden syrup, 100 grams/3.5 oz treacle, 1 tsp cinnamon, 2 heaped tsp ground ginger and 125 grams/4.4 oz dark muscovado sugar and stir until well combined.
Take off the heat and 250 mls milk, 2 eggs and 1 tsp bicarb of soda dissolved (in 30 mls water). By adding the milk first you make sure the mixture is cool enough not to cook the eggs. Mix well.
Put 300 grams/10.5 oz self raising flour in a mixing bowl and pour the warm liquid into the bowl. Mix well until smooth.
Pour into your tin and bake for about 45 - 50 mins until risen and firm and a cocktail stick comes out clean. The top will be sticky. Wrap up when cool and leave for 24-48 hours to get stickier.
Notes
Strangely you can get large and small 2lb tins. Mine is one of the larger ones. If yours is smaller and the cake mixture is looking as if it will reach the top of the liner as you are pouring it in then stop 2 cm before the top of the liner and make some muffins with the left over mixture.