A piece of cake

What’s the origin of the phrase ‘Piece of cake’?

This phrase is of American origin. At least, the earliest citation of it that I can find is from the American poet and humorist Ogden Nash’s Primrose Path, 1936:

“Her picture’s in the papers now, And life’s a piece of cake.”

The choice of cake or pie as a symbol of ease and pleasantry is well represented in the language. Other phrases along the same lines include:

As easy as pie

Pie in the sky

A cake-walk

That takes the cake/biscuit’.

See other phrases that were coined in the USA.