250ml double creamsubstitute with milk for a lighter option
3eggsor 2 if using large eggs
Lightly grease the inside of the slow cooker pot with some of the softened butter until about half way up the sides.
Butter both sides of the slices of bread and then cut each slice into six pieces. Roughly layer these in the slow cooker pot, sprinkling the sultanas throughout as you make up the layers.
In a bowl, whisk the eggs and add 50 grams of the sugar, beating continuously. Add the milk, cream and mixed spice and stir well. Pour the custard mixture over the bread in the pot ensuring that all the pieces are soaked. The top layer of the pudding should not be entirely submerged. Sprinkle the remaining sugar over the top of the pudding.
Place a clean tea towel under the lid of the pot to absorb any excess moisture, then cook for 3½ hours on low, or 2 hours on high.
When it's cooked through the pudding will have set and the edges will be starting to brown and shrink away from the sides of the pot. To brown the top of the pudding, transfer to a grill pan and place under a medium grill for 1 to 2 minutes.