Heat the slow cooker on high for 20 mins. Carefully rub the basin of your slow cooker with butter. Make the sponge by combining the melted butter with both sugars, the eggs and milk, then fold in the flour, baking powder, ginger and cinnamon. Whisk to remove any lumps if needed, then pour into your slow cooker.

For the sauce, mix the cornflour with 1 tsp water, then set aside. Combine the sugar and ginger with 350ml boiling water until the sugar has dissolved. Mix in the cornflour paste, then pour over the batter.

Cook on high for 1 hr 30 mins- 2 hrs 30 mins (this will vary depending on your slow cooker), until the sponge has set and is firm to the touch. To serve, pour over some double cream, if you like.