Cooking time really depends on your slow cooker. Every slow cooker is different. Once you know how long your slow cooker takes to bake cakes, use that as a guide. If cooking one for the first time, check regularly (every 15-20 minutes) to make sure it isn't burning. Use the tea towel under the lid to catch drips and stop the top getting wet and soggy. Check the centre of the cake with a skewer or knife to see when it is cooked through. If the top still seems a bit wet, cook for another ten minutes then check again.