Line your slow cooker pot with baking paper. I used a round 3.5 litre slow cooker.
Cream the butter and sugar together until light and fluffy.
200 g unsalted butter, 160 g golden caster sugar, 40 g dark muscovado sugar
Add the eggs one by one and mix in well.
4 medium free-range eggs
Fold in the flour, ginger, allspice and crystallised ginger until well combined.
200 g self-raising flour, 1 tsp ground ginger, 1 tsp ground allspice, 20 g crystallised fiery ginger
Add the golden syrup and mix through.
1 tbsp golden syrup
Pour the mixture into the lined slow cooker pot. Put on the lid and put a tea towel under the lid to catch drips and stop condensation dripping onto the top of the cake.
Cooking time: Depends on your slow cooker and whether it cooks quickly or slowly - I cooked my cake for 1 hour 20 on high then switched to low and continue to cook for 2 hours. Switch to low to prevent the edges burning and then continue to cook until the cake is no longer wet on top. Check regularly and use a skewer or knife to test the cake to see if it is cooked through. Look out for burning round the edges too. Remove from the slow cooker using the edges of the baking paper and allow to cool.