It's a piece of soup vs I's a cake of soup

Some examples from the web:

• The pieces of the soup tureen are in a glass case.
• Give you this gold piece for half the soup.
• It's a piece of paper.
• It's a piece of my meteorite.
• Janie, it's a piece of paper.
• I - It's a piece of plastic.
• It's a piece of paper.
• Now... it's a piece of roadside litter.
• - It's about a piece of plastic.
• It's a piece of paper with holes in specific places.
• It's a piece of rubber.
• It's a piece of junk that barely moves.
• It's a piece of cake compared to all this promotion.
• It's a piece of an alloy tumbler locking mechanism.
• It's just a piece of cloth.
• It's just a piece of cake.
• Then it's like cuttin' through a piece of firewood.
• It's a piece of cake.
• It's supposed to look straight like a piece of bamboo.
• It's because someone might slip a piece of glass into it.

Some examples from the web:

• ! Who invented Cake Soup and Roulade Roulette?
• You loved the cakes and the chicken soup your granny made.
• You can stir-fry this rice cake or make soup with it.
• He's baked a cake of remorse.
• He's baked a cake of remorse.
• About six months ago a guy slipped on a cake of soap in his bathtub and knocked himself cold and was drowned.
• Did you ever see a cake of soap that big?
• If I had always told the truth, Pete, I would now be a cake of soap.
• Mr President, Commissioner, Mr President-in-Office of the Council, on 18 January 2000 I brought you a cake of crude oil from the Erika which had come ashore on a beach.
• Here is a cake of oil sent by someone living on the French island of Noirmoutier who wrote to me as follows: With every tide, the beach is covered with heavy fuel oil which has leaked out of the Erika.
• Children must learn, for example, that, as well as a hot vegetable, carrots can also be enjoyed in the form of soup, salad, cakes or in baked dishes.
• Democracy is not unlike a cake.
• Your boyfriend sent you a cake.
• A cake paradise for your taste buds.
• Wisdom coming from a cake fiend.
• Jennifer wants a cake plate for our wedding.
• Data, sometimes a cake is just a cake.
• I'm all out of soup.
• Church should make you happy, like a warm mug of soup.
• A bowl of soup becomes a stain.