Heat the oven to 200`c and line 2 x 20cm round tins with baking paper. To make the cake batter, start by mixing together the egg, egg whites, lemon essence and ½ of the milk in a bowl and put aside. Next, beat the butter till soft then mix in the sugar. Sift in the flour, baking powder and salt and mix together before mixing in the remaining ½ milk. Scrape down the bowl then mix in the egg mixture prepared earlier till smooth. Finally, mix in the confetti and evenly spoon into the prepared tins. Bake in the oven for 25-30 minutes. Allow to cool and meanwhile prepare the frosting by beating together the butter, icing sugar and vanilla till light then beat in the cream cheese till smooth. Cut the 2 cakes in half and sandwich together with the jam, then sandwich the 2 cakes with a little of the frosting. Place onto a cake stand and frost the entire cake using a palette knife. Finish of by decorating with the confetti and coloured sweets.