1.Lightly grease a deep 20cm round springform pan.
2.Cream butter, vanilla essence, sugar, egg and syrup in small bowl with electric mixer until light and fluffy. Transfer to a large bowl, stir in half the sifted flour with half the milk, then stir in remaining flour and milk.
3.Place half the mixture into separate bowl, stir in blended sifted cocoa and extra milk. Drop alternate spoonfuls of mixture into prepared pan, run knife through the mixture to give marbled effect. Bake in moderate oven for about 45 minutes.
4.Remove cake from oven, place a layer of marshmallows evenly on top of cake, return to oven for about a further 5 minutes or until marshmallows are beginning to melt. Cool 5 minutes, remove side of pan, drizzle with combined melted chocolate and extra butter.
Keeping time: 3 days.Note