If doing something is described as a piece of cake, it means it is easy to do.
Changing the wheel on the car was a piece of cake – I was happy to help!
I don't know what all the fuss was about – the exam was a piece of cake! I had half an hour to spare.
The icing on the cake describes something that makes a good situation even better.
It was great to win the match but the icing on the cake was getting promoted to the Premiership!
According to the Guinness World Records, the world's largest wedding cake weighed 6.818 tonnes and was made by chefs at a hotel in Connecticut in the USA.