I did it the morning of the party because i was paranoid something would happen to it in the fridge overnight with the butter icing... so i just whipped up the icing fresh, made the cake the day before... and had plenty of time to decorate,, a little tip.. with the grass you can put coconut in a glad bag and add green colouring to get a bit of texture in the grass ( looks great) and the same with the water...

I made a NUmber 2 for DS with freen grass, chocolate (brown ) racing track and the cake was rainbow.. If you want to make a rainbow cake... the kids love it !!!! Seperate your cake mixture into different bowls, use a little food colouring to your taste, and then pour the colours one of top of the other in the pan... I did pink , blue and green and it looked great, even had some purple through it....